diff --git a/src/pg_rad/background/background.py b/src/pg_rad/background/background.py
index a7cfa5c..facbadf 100644
--- a/src/pg_rad/background/background.py
+++ b/src/pg_rad/background/background.py
@@ -11,7 +11,8 @@ def generate_background(
     cps_array: np.ndarray,
     detector: Detector,
     energy_keV: float,
-    lam_inp: int | None = None
+    lam_inp: int | None = None,
+    seed: int | None = None
 
 ) -> np.ndarray:
     """
@@ -23,7 +24,7 @@ def generate_background(
     else:
         lam = lam_inp
 
-    rng = np.random.default_rng()
+    rng = np.random.default_rng(seed=seed)
     return rng.poisson(lam=lam, size=cps_array.shape)
 
 
diff --git a/src/pg_rad/inputparser/parser.py b/src/pg_rad/inputparser/parser.py
index aea77e7..159a69f 100644
--- a/src/pg_rad/inputparser/parser.py
+++ b/src/pg_rad/inputparser/parser.py
@@ -125,7 +125,7 @@ class ConfigParser:
             )
 
         if (
-            seed is not None or
+            seed is not None and
             (isinstance(seed, int) and seed <= 0)
         ):
             raise InvalidConfigValueError(
diff --git a/src/pg_rad/main.py b/src/pg_rad/main.py
index f83be0f..7fb3725 100644
--- a/src/pg_rad/main.py
+++ b/src/pg_rad/main.py
@@ -2,6 +2,7 @@ import argparse
 import logging
 import sys
 
+from numpy.random import SeedSequence
 from pandas.errors import ParserError
 
 from pg_rad.exceptions.exceptions import (
@@ -77,12 +78,18 @@ def main():
                 gamma_energy_keV: 661
 
         detector: LU_NaI_3inch
+
+        options:
+          seed: 1234
         """
     elif args.config:
         input_config = args.config
 
     try:
         cp = ConfigParser(input_config).parse()
+        if cp.options.seed is None:
+            entr = SeedSequence().entropy
+            cp.options.seed = int(str(entr)[:6])
         landscape = LandscapeDirector.build_from_config(cp)
         output = SimulationEngine(
             landscape=landscape,
diff --git a/src/pg_rad/physics/fluence.py b/src/pg_rad/physics/fluence.py
index 7bc04dc..ae37b3b 100644
--- a/src/pg_rad/physics/fluence.py
+++ b/src/pg_rad/physics/fluence.py
@@ -109,7 +109,8 @@ def calculate_counts_along_path(
     detector: "Detector",
     velocity: float,
     points_per_segment: int = 10,
-    bkg_cps_input: int | None = None
+    bkg_cps_input: int | None = None,
+    seed: int | None = None
 ) -> Tuple[np.ndarray, np.ndarray]:
     """Compute the counts recorded in each acquisition period in the landscape.
 
@@ -152,14 +153,16 @@ def calculate_counts_along_path(
 
     if bkg_cps_input is None:
         bkg = generate_background(
-            cps, detector, landscape.point_sources[0].isotope.E
+            cps, detector, landscape.point_sources[0].isotope.E,
+            seed=seed
         )
     elif bkg_cps_input == 0:
         bkg = bkg_cps_input
     else:
         bkg = generate_background(
             cps, detector, landscape.point_sources[0].isotope.E,
-            lam_inp=bkg_cps_input
+            lam_inp=bkg_cps_input,
+            seed=seed
         )
 
     cps_with_bg = cps + bkg
diff --git a/src/pg_rad/plotting/result_plotter.py b/src/pg_rad/plotting/result_plotter.py
index ad595f2..5a76e42 100644
--- a/src/pg_rad/plotting/result_plotter.py
+++ b/src/pg_rad/plotting/result_plotter.py
@@ -116,6 +116,7 @@ class ResultPlotter:
             ["Air density (kg/m^3)", round(self.landscape.air_density, 3)],
             ["Total path length (m)", round(self.landscape.path.length, 3)],
             ["Readout points", len(self.count_rate_res.integrated_counts)],
+            ["Seed", self.count_rate_res.seed],
             ["Mean background cps", round(self.count_rate_res.mean_bkg_cps, 3)]
         ]
 
diff --git a/src/pg_rad/simulator/engine.py b/src/pg_rad/simulator/engine.py
index c37cc8d..634ff64 100644
--- a/src/pg_rad/simulator/engine.py
+++ b/src/pg_rad/simulator/engine.py
@@ -48,7 +48,8 @@ class SimulationEngine:
                 self.landscape,
                 self.detector,
                 velocity=self.runtime_spec.speed,
-                bkg_cps_input=self.sim_spec.bkg_cps
+                bkg_cps_input=self.sim_spec.bkg_cps,
+                seed=self.sim_spec.seed
             )
         )
 
@@ -59,7 +60,8 @@ class SimulationEngine:
             sub_points,
             cps,
             int_counts,
-            mean_bkg_counts
+            mean_bkg_counts,
+            self.sim_spec.seed
         )
 
     def _calculate_point_source_distance_to_path(self) -> List[SourceOutput]:
diff --git a/src/pg_rad/simulator/outputs.py b/src/pg_rad/simulator/outputs.py
index 7ec364b..1822ebe 100644
--- a/src/pg_rad/simulator/outputs.py
+++ b/src/pg_rad/simulator/outputs.py
@@ -12,6 +12,7 @@ class CountRateOutput:
     cps: List[float]
     integrated_counts: List[float]
     mean_bkg_cps: List[float]
+    seed: int
 
 
 @dataclass