Rotavirus is one of the most common causes of childhood diarrheal disease and deaths in sub-Saharan Africa. This article reviews community- and hospital-based surveillance of rotavirus disease in Bissau, Guinea-Bissau, West Africa. Here, rotavirus infections exhibit a seasonal pattern, with annual epidemics occurring during the relatively dry and cooler months, from January to April, and few cases registered from May to December. Most children (74%) experience their first infection before the age of 2 years, and rotavirus has been identified as the most pathogenic of all diarrheal agents during 2 large prospective studies involving several hundred children 48 h after admission).