Background: Breastfeeding has long-term benefits, such as reducing obesity, allergies, asthma, wheezing, inflammatory bowel disease, diabetes, cardiovascular disease and effecting on brain development .This study aimed to investigate the relationship between exclusive breastfeeding and mental concentration in first and second grade primary school children. Methods: In this cross-sectional study, 90 students (7-8 years old) were studied in Mashhad, Iran. The history and duration of breastfeeding were asked from children’s mothers, and their mental concentration and short term memory were measured by Toulouse Pieron and Digit learning tests, respectively. Results: The mean of the breastfeeding period was 5.72 ± 6.89 month and the mean of total scores
was 51.2 ± 32.44 for Toulouse Pieron test and 8.57 ± 6.52 for Digit learning test in all participants. The correlation between the Toulouse Pieron and Digit learning test, and breastfeeding history indicated that exclusive breast-fed children showed higher test results and therefore, better mental concentration and short term memory (P < 0.001). Conclusion: Based on the findings, exclusive breastfeeding has a positive effect on mental concentration and short term memory with respect to its duration.