Ramadan is a month in the Islamic calendar when Muslims fast during daylight hours. We used data from the surveillance system of the International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka Hospital in Dhaka, Bangladesh, a predominantly Muslim country, to compare the etiology and clinical presentation of patients who presented with diarrhea during Ramadan to that of control periods, defined as the 30 days immediately before Ramadan. The proportion of infecting pathogens was largely the same, although Shigella spp. were less likely to be identified during Ramadan. Clinical presentations during Ramadan among adult Muslim diarrheal patients were also comparable to those admitted during control periods. A subgroup of cholera patients who presented after sunset during Ramadan had a shorter duration of diarrhea and higher prevalence of severe thirst, drowsiness, and severe dehydration. Our findings suggest that Ramadan has few effects on the profile of enteric pathogens and clinical features of adults seeking medical care for diarrhea.