Introduction: Diarrhea is an increase in frequency of bowel movements or an increase in the liquidity (greater looseness) of stool. Although changes in frequency of bowel movements and looseness of stools can vary independently of each other. Changes often occur in both. Acute diarrhea (including gastroenteritis) remains one of the commonest causes of death among infants and children in developing countries where poor sanitation, deficiency of clean drinking water, poverty and illiteracy are key factors. Viral infection remains another very important cause. In Europe, most cases take a mild to moderately severe course, and fatal outcomes are extremely rare. Objective: To find out the frequency of diarrhea in infants less than six months of age cross-sectional study (Descriptive study). Methods: A hospital based descriptive study was conducted from 1st December to 1st February 2018 in Pediatric Unit of BVH Bahawalpur. Source of population were 100 children under six months of age. Data analysis was made manually and frequency of diarrhea was calculated. Results: The frequency of diarrhea was more in infants 0-2 months. The frequency was low in infants who were on exclusive breast feed the diarrheal frequency was high in infants of rural areas. Female were showing resistance to diarrhea as compared to male. Hand washing before weaning or breast feeding and clean water supply caused a reduction in the frequency of diarrhea. Conclusion: Breast feeding, clean drinking water, proper hygiene and literacy must be promoted to prevent diarrhea.