diff --git a/abcpmc/sampler.py b/abcpmc/sampler.py
index 791a6f1..e324a4d 100644
--- a/abcpmc/sampler.py
+++ b/abcpmc/sampler.py
@@ -169,11 +169,13 @@ class Sampler(object):
     particle_proposal_cls = ParticleProposal
     particle_proposal_kwargs = {}
     
-    def __init__(self, N, Y, postfn, dist, threads=1, pool=None):
+    def __init__(self, N, Y, postfn, dist, threads=1, pool=None, postfn_kwargs={}, dist_kwargs={}):
         self.N = N
         self.Y = Y
         self.postfn = postfn
+        self.postfn_kwargs = postfn_kwargs # keyword arguments for postfn 
         self.dist = dist
+        self.dist_kwargs = dist_kwargs  # keyword arguments for distance metric
         self._random = np.random.mtrand.RandomState()
 
         if pool is not None:
@@ -264,7 +266,9 @@ class _RejectionSamplingWrapper(object):  # @DontTrace
     
     def __init__(self, sampler, eps, prior):
         self.postfn = sampler.postfn
+        self.postfn_kwargs = sampler.postfn_kwargs
         self.distfn = sampler.dist
+        self.distfn_kwargs = sampler.dist_kwargs
         self._random = sampler._random
         self.Y = sampler.Y
         self.eps = np.asarray(eps)
@@ -280,8 +284,8 @@ def __call__(self, i):
         cnt = 1
         while True:
             thetai = self.prior()
-            X = self.postfn(thetai)
-            p = np.asarray(self.distfn(X, self.Y))
+            X = self.postfn(thetai, **self.postfn_kwargs)
+            p = np.asarray(self.distfn(X, self.Y, **self.distfn_kwargs))
             if np.all(p <= self.eps):
                 break
             cnt+=1