diff --git a/pipit/trace.py b/pipit/trace.py
index 2b4f111a..6db60d94 100644
--- a/pipit/trace.py
+++ b/pipit/trace.py
@@ -861,3 +861,166 @@ def detect_pattern(
             patterns.append(match_original)
 
         return patterns
+
+    def critical_path_analysis(self):
+        self._match_events()
+
+        instant_recv_events = ["MpiRecv", "MpiIrecv"]
+        recv_events = ["MPI_Recv", "MPI_Irecv"]
+        send_events = ["MPI_Send", "MPI_Isend"]
+        collective_functions = [
+            "MPI_Allgather",
+            "MPI_Allgatherv",
+            "MPI_Allreduce",
+            "MPI_Alltoall",
+            "MPI_Alltoallv",
+            "MPI_Alltoallw",
+            "MPI_Barrier",
+            "MPI_Bcast",
+            "MPI_Gather",
+            "MPI_Gatherv",
+            "MPI_Iallgather",
+            "MPI_Iallreduce",
+            "MPI_Ibarrier",
+            "MPI_Ibcast",
+            "MPI_Igather",
+            "MPI_Igatherv",
+            "MPI_Ireduce",
+            "MPI_Iscatter",
+            "MPI_Iscatterv",
+            "MPI_Reduce",
+            "MPI_Scatter",
+            "MPI_Scatterv",
+            "MPI_Exscan",
+            "MPI_Op_create",
+            "MPI_Op_free",
+            "MPI_Reduce_local",
+            "MPI_Reduce_scatter",
+            "MPI_Scan",
+            "MPI_File_iread_at_all",
+            "MPI_File_iwrite_at_all",
+            "MPI_File_iread_all",
+            "MPI_File_iwrite_all",
+            "MPI_File_read_all_begin",
+            "MPI_File_write_all_begin",
+            "MPI_File_write_all_end",
+            "MPI_File_close",
+        ]
+
+        critical_paths = []
+        critical_path = []
+        last_event = None
+        leave_events = self.events[(self.events["Event Type"] == "Leave")]
+        num_of_processes = leave_events["Process"].astype(int).max()
+
+        if "MPI_Finalize" in self.events["Name"].values:
+            last_event = self.events[
+                (self.events["Event Type"] == "Leave")
+                & (self.events["Name"] == "MPI_Finalize")
+            ].iloc[-1]
+        else:
+            last_event = self.events[self.events["Event Type"] == "Leave"].iloc[-1]
+        last_name = last_event["Name"]
+        last_process = last_event["Process"]
+        last_timestamp = last_event["Timestamp (ns)"]
+        critical_path.append(last_event)
+        after_recieve = False
+        after_collective = False
+        # Main loop to trace back
+        while True:
+            # Filter for events from the same process before the last timestamp
+            candidate_events = leave_events[
+                (leave_events["Process"] == last_event["Process"])
+                & (leave_events["Timestamp (ns)"] < last_event["Timestamp (ns)"])
+            ]
+
+            # obtain the latest function after the collective function call.
+            # we basically do the something similar to starting with MPI_Finalize
+            # but this time we use a different function.
+            if after_collective:
+                candidate_name = candidate_events.iloc[-1]["Name"]
+                candidate_events = leave_events[
+                    (leave_events["Name"] == candidate_name)
+                    & (leave_events["Timestamp (ns)"] < last_event["Timestamp (ns)"])
+                ]
+
+            # No more events to trace back from.
+            if candidate_events.empty:
+                break
+
+            # Select the last event from the candidates if
+            # we the previous event is not a receive.
+            if not after_recieve:
+                last_event = candidate_events.iloc[-1]
+                critical_path.append(last_event)
+
+            # If we continue after a receive function.
+            if last_event["Name"] in recv_events:
+                # Get the corresponding instant event for the recv function.
+                last_instant_event = self.events[
+                    (self.events["Event Type"] == "Instant")
+                    & (self.events["Timestamp (ns)"] < last_timestamp)
+                    & (self.events["Process"] == last_process)
+                    & (self.events["Name"].isin(instant_recv_events))
+                ]
+                # Sometimes recv function have some instant events which
+                # do not include the sender information. We ignore them.
+                if last_instant_event.empty:
+                    continue
+                else:
+                    last_instant_event = last_instant_event.iloc[-1]
+
+                # Get the corresponding send event.
+                last_event = self.events[
+                    (self.events["Timestamp (ns)"] < last_timestamp)
+                    & (
+                        self.events["Process"]
+                        == last_instant_event["Attributes"]["sender"]
+                    )
+                    & (
+                        self.events["Name"].isin(send_events)
+                        & (self.events["Event Type"] == "Leave")
+                    )
+                ].iloc[-1]
+                last_timestamp = last_event["Timestamp (ns)"]
+                last_process = last_event["Process"]
+
+                after_receive = True
+                after_collective = False
+                critical_path.append(last_event)
+                pass
+
+            # Restart the detection after a collective function.
+            if last_event["Name"] in collective_functions:
+                critical_paths.append(critical_path)
+                critical_path = []
+                after_collective = True
+                after_receive = False
+
+            start_times = []
+            check_if_done = leave_events[leave_events["Name"] == last_event["Name"]]
+            for start_time in check_if_done.iloc[0 : num_of_processes + 1][
+                "Timestamp (ns)"
+            ]:
+                start_times.append(start_time)
+
+            # Exit if we have traced back to the beginning
+            leave_events = leave_events.reset_index(drop=True)
+            if (
+                leave_events[
+                    (leave_events["Timestamp (ns)"] == last_event["Timestamp (ns)"])
+                ].index
+                <= num_of_processes + 1
+            ):
+                if (
+                    last_event["Name"] == leave_events.iloc[0]["Name"]
+                    and last_event["Timestamp (ns)"] in start_times
+                ):
+                    critical_paths.append(critical_path)
+                    break
+
+        critical_dfs = []
+        for critical_path in critical_paths:
+            if len(critical_path) > 1:
+                critical_dfs.append(pd.DataFrame(critical_path))
+        return critical_dfs