diff --git a/tmt/steps/report/reportportal.py b/tmt/steps/report/reportportal.py
index 41e67280fa..70ef54d95d 100644
--- a/tmt/steps/report/reportportal.py
+++ b/tmt/steps/report/reportportal.py
@@ -47,6 +47,12 @@ def _filter_invalid_chars(data: str) -> str:
         '',
         data)
 
+def _filter_log_per_size(data: str, limit: int) -> str:
+    size = len(log)
+    if size > limit:
+        return (f"Log file was not uploaded to ReportPortal because its size {size} bytes"
+                f"exceeds {self.data.log_size_limit} bytes.")
+    return log
 
 @dataclasses.dataclass
 class ReportReportPortalData(tmt.steps.report.ReportStepData):
@@ -142,6 +148,14 @@ class ReportReportPortalData(tmt.steps.report.ReportStepData):
              (e.g. 'Idle'). 'To Investigate' is used by default.
              """)
 
+    log_size_limit: Optional[str] = field(
+        option="--log-size-limit",
+        metavar="LOG_SIZE_LIMIT",
+        default=_str_env_to_default('log_size_limit', '1048576'),
+        help="""
+             Size limit in bytes for log upload to ReportPortal. The default is 1048576 bytes (1 MB).
+             """)
+
     exclude_variables: str = field(
         option="--exclude-variables",
         metavar="PATTERN",
@@ -590,15 +604,20 @@ def go(self, *, logger: Optional[tmt.log.Logger] = None) -> None:
                             response = self.rp_api_post(
                                 session=session,
                                 path="log/entry",
-                                json={"message": _filter_invalid_chars(log),
+                                json={"message": _filter_invalid_chars(
+                                                     _filter_log_per_size(log,
+                                                                          int(self.data.log_size_limit))),
                                       "itemUuid": item_uuid,
                                       "launchUuid": launch_uuid,
                                       "level": level,
                                       "time": result.end_time})
 
                             # Write out failures
+                            failures = result.failures(log)
                             if index == 0 and status == "FAILED":
-                                message = _filter_invalid_chars(result.failures(log))
+                                message = _filter_invalid_chars(
+                                              _filter_log_per_size(result.failures(log),
+                                                                   int(self.data.log_size_limit)))
                                 response = self.rp_api_post(
                                     session=session,
                                     path="log/entry",