Research was conducted on the biological control of the pest insect Helicoverpa armigera on small farms in Kenya, from 1988 to 1990. An extensive review is included of the information available on the natural enemies of H. armigera in Africa. The taxonomy, distribution, biology, alternative hosts or prey, host plant associations and secondary natural enemies are detailed for all recorded natural enemies. Different aspects are summarized and evaluated for the total natural enemy complex. The ecology of Helicoverpa armigera and its natural enemies was studied in 4 crops commonly grown on small farms in Kenya: cotton, sunflower, maize and sorghum. A number of parasites and predators were recorded, but their impact was generally low. Trials were conducted to determine the role of predation and other mortality factors in sunflower and cotton. To evaluate predators at greater pest densities, a series of predator exclusion cages and open control cages were inoculated with H. armigera eggs. Implications for integrated pest management and research priorities are discussed.