Qualitative methods were used to gather data on community perceptions of malaria in Morong, Bataan. People recognised an illness which they called "malarya' through a discrete set of symptoms: high fever and intense chills, with or without a severe headache. Self-medication was common. Enquiry into perceptions of cause and prevention of the disease revealed a complex mixture of beliefs involving environmental conditions, the mosquito vector and parasites, but included also various ideas about dirty water, diet, hunger and conditions of hygiene. The implications of these findings for disease control, and the relationship between knowledge and practices, are discussed.