Purpose: Propranolol is the most widely used treatment for cardiovascular diseases. Dosage range in our patients is usually less than the amount mentioned in references. The aim of the present study was to clarify whether pharmacokinetic differences are able to justify the need for the fewer doses in our patients or not.Methods: Twenty healthy volunteers (10 male) at heart center of Mazandaran University of Medical Sciences were studied. Samples of blood were collected before a single oral dose (40 mg) of Propranolol. Blood samples were taken up to 9 hours after dose. Total plasma concentration of Propranolol was measured by HPLC. Population Pharmacokinetic analysis was performed using population pharmacokinetics modeling software P-Pharm.Results: The mean value for oral plasma clearance (CL/F) was 126.59 ml/hr. The corresponding values for apparent volume of distribution (V/F), t1/2 beta, maximum blood concentration (C max), and time to reach the maximum blood concentration (T max) were 334.12 Lit, 1.98 hr, 40.25 ng/ml, and 1.68 hr, respectively. The observed mean values of V/F of propranolol in the present study were comparable with those reported in the literature. However, the mean values of CL/F of propranolol in current study was significantly higher than those reported in other population (P-value<0.001).Conclusion: This study has confirmed that the pharmacokinetic differences are not able to justify over-responsiveness of Iranian population to propranolol. Pharmacodynamic differences in responding to beta blocker drugs by Renin secretion or having a different sensibility to beta receptors might play a role in making our population have a different response to propranolol.