Background: The phimosis prevalence is increasing every year. One of using disposable diapers side effects is phimosis. Aim : Authors are interested in further researching about correlation between phimosis incidence and use of disposable diapers in children at H. Adam Malik Hospital, Medan. Methods : This study is an analytic study with cross-sectional design at Division of Pediatric Surgery, Department of Surgery, USU Medical Faculty, H. Adam Malik Hospital, Medan after proposal was approved by USU Medical Faculty research ethics committee. The study sample was children with phimosis who used or did not use disposable diapers, used technique total sampling. All results are displayed in tabulation. For inferential analysis of hypothesis testing, chi square test is used. Results: There are 24 children (33.3%) who use less than 6 diapers per day, 16 of them (22.2%) have pathological phimosis. 48 children (66.7%) who use more than 6 diapers per day, 18 of them (25%) had pathological phimosis. Based on analysis, there is a statistically significant effect between disposable diapers on phimosis incidence in children with p>0.025. Conclusion: There was a significant correlation between use of disposable diapers and phimosis incidence in children at H. Adam Malik Hospital Medan.