Background: Prostate cancer is the most frequently occurring cancer among males in economically developedcountries. Among the several risk factors that have been suggested, only age, ethnicity, diabetes, and familyhistory of prostate cancer are well-established and primary prevention of this disease is limited. Prior studieshad shown that dietary intake could be modified to reduce cancer risk. We conducted a hospital-based, casecontrolstudy to examine the association between dietary patterns and prostate cancer risk in Iran. Materials and Methods: A total of fifty patients with prostate cancer and a hundred controls underwent face-to-face interviews.Factor analysis was used to determine the dietary patterns. Multivariate logistic regression was used to estimateodds ratios (ORs) and 95% confidence intervals (CIs). Results: We defined two major dietary patterns in thispopulation: ‘western diet’(high in sweets and desserts, organ meat, snacks, tea and coffee, French fries, salt,carbonated drinks, red or processed meat) and ‘healthy diet’ (high in legumes, fish, dairy products, fruits andfruit juice, vegetables, boiled potatoes ,whole cereal and egg). Both Healthy and western pattern scores weredivided into two categories (based on medians). Higher scores on Healthy pattern was marginally significantlyrelated to decreased risk of prostate cancer (above median vs below median, OR =0.4, 95%CI=0.2-1.0). Anincreased risk of prostate cancer was observed with the higher scores on the Western pattern (above median vsbelow median, OR=4.0, 95%CI=1.5-11.0). Conclusions: The results of this study suggested that diet might beassociated with prostate cancer among Iranian males.