Background: Prostate cancer is the third most common malignancy in men worldwide. Despite being a helpful biomarker in prostate cancer, prostate specific antigen (PSA) is affected by different factors including age, lifestyle, geographical region and ethnicity. Objective: To determine the age specific serum PSA level among healthy Northern Iranian men and to compare the results of our study with the findings of other populations in the world. Methods: A total of 1271 men who were referred for routine check-up in a multispecialty hospital in the city of Rasht, in Northern Iran, were evaluated for their PSA levels by commercial ELISA method. Results: The normal age related prostate specific antigen range (0-95th percentile) in our study was 0.0-0.62 in men younger than 40 yrs; 0.0-0.75 ng/ml in 40-49 yrs; 0.0-0.91 ng/ml in 50-59 yrs; 0.0-1.33 ng/ml in 60-69 yrs; 0.0-1.45 ng/ml in 70-79 yrs group and 0.0-1.93 in subjects older than 80 yrs. Conclusion: The present study revealed the lowest upper limit of PSA level in all age groups in comparison to populations from different countries.