Diarrhea is a leading cause of Infant and under 5 mortality and morbidity worldwide. It is a preventable health problem with its Risk factors varying with context. These risk factors need to be understood for targeted planning and implementation of prevention strategies to reduce the global burden of the disease. A hospital based descriptive cross sectional survey was conducted among 134 mother’s infant pair to identify the prevalence and associated risk factors of acute diarrhea among infants in Parsa, Nepal using a pretested structured interview schedule via face to face interview technique. The obtained data were analyzed by descriptive and inferential statistics using SPSS 16 version. The two week prevalence of diarrheal morbidity among infants was 17.9%. Age of the infant (COR: 2.91, 95% CI: 1.11– 7.58), gender (COR: 4.56, 95% C.I: 1.58–13.08), bottle feeding (COR: 0.312, 95% CI: 0.12–0.78) ,no current breast feeding (COR: 3.52, 95% CI: 1.32–9.4), not completing immunization for age ((COR: 2.21, 95% CI: 0.81–6.25), no hand washing facilities (COR: 1.603, 95% CI:0.4–6.42), no separate kitchen (COR: 3.7, 95% CI: 1.26–10.89) were the significant risk factors of acute diarrhea among infants. Intervention on potential risk factors such as promotion of nutrition through proper breast feeding along with colostrum feeding, avoidance of bottle feeding, proper complementary feeding practice, immunization according to age, proper hand washing and promotion of hygiene and environment sanitation is recommended as simple and cost effective means of alleviating the problem