An investigation of an epidemic of El Tor cholera serotype Ogawa, was conducted in an institution for the mentally handicapped in Alabang, Metro Manila in the Philippines. Thirteen of the 251 inmates were afflicted—an overall attack rate of 5%. There was one death. Only those with mental age of 6 years or less were ill. The source of infection and the mode of transmission were not conclusively identified. However, the sequence of events suggests that it spread initially from person-to-person and then was foodborne.