It is well known that dietary factors can affect male fertility. The aim of this study was investigating the effect of Mediterranean diet on sperm quality. Methods: This cross-sectional study was conducted on 218 men with infertility aged 20-50. A 168-item food frequency questionnaire (FFQ) was used to evaluate dietary intakes. Mediterranean diet scores were calculated based on the participant’s dietary intake. The evaluation of anthropometric and biochemical variables was performed through standard methods. To evaluate the relationship between Mediterranean dietary patterns and sperm parameters, the multivariate logistic regression controlled for potential confounders was used. Results: The prevalence of sperm’s low concentration in people with low, moderate, and high adherence to the Mediterranean diet was 43.4%, 34% and 25.9%, respectively. Participants in the highest tertile of adherence to the Mediterranean diet had lower odds of sperm low concentration (odds ratio: 0.37; 95% confidence interval: 0.15–0.91 P=0.02) compared with those in the lowest tertile after adjusting for potential confounders including energy intake, body mass index (BMI), smoking, age, level of education and physical activity. This association was observed between increasing trend adherence to the Mediterranean diet and decreasing the odds of sperm low concentration after full adjustments (odds ratio: 0.60; 95%, confidence interval: 0.98–0.94, Ptrend=0.02). Conclusion: In the present study, the authors observed a protective relation between Mediterranean diet and sperm’s low concentration. However, the association between adherence to this diet and other sperm parameters is unexplored. In future, more investigations are needed in this era.