A survey of the natural enemies of the main malaria vector in Kenya, Anopheles gambiae Giles, revealed the occurrence of a fungal pathogen in field populations of mosquito larvae. Light and scanning electron microscopy was used in the examination of sporangia of the fungus in determining its identity as Coelomomyces indicus Iyengar (Order: Blastocladiales; Family: Coelomomycetaceae). The resting sporangia were found in the thoracic and abdominal cavities of the larvae. A mortality of 63% or higher was found to occur among the larvae of A. gambiae in a two season observation along the Kenyan coast. The authors stress the need for more intensified ecological and laboratory studies aimed at developing C. indicus as a biocontrol agent.