A survey involving more than 129 farmers was carried out in 1998 and 1999 in Ouémé, Benin, to investigate the importance of pests and diseases as constraints to cowpea (Vigna unguiculata (L.) Walp.) production. Results indicated that in the Ouémé valley Sclerotium rolfsii Sacc. and Aphis craccivora Koch are specific concerns. Weeds such as justicia anselliana (Nees) T. Anders, Ipomoea aquatica Forsskal and Commelina erecta L. were also reported as being troublesome. On the Ouémé plateau Imperata cylindrica L. Beauv. was reported to be a major weed. Callosobruchus maculatus Fab. and Bruchidius atrolineatus Fab. may cause up to 100% loss within a few months in storage. Birds and rodents were also reported. In certain areas on the plateau, farmers have developed pest control methods based on indigenous knowledge. In the valley the population density of Eichhornia crassipes (Mart) Solms. during flooding is used by farmers to predict aphid infestation. A number of plant species used to protect cowpea were reported. In Gbékandji village, natural enemies such as Rhabdepyris sp., Evania sp., and Chelonus sp., were observed. They were rare in the valley, where farmers rely on chemical control. Farmers reported alternative hosts of cowpea pests from the families Fabaceae (eight species), Mimosaceae (two species), Ceasalpiniaceae (five species), Capparidaceae (two species) and Pontederiaceae (one species). Based on the hierarchy of constraints, sustainable integrated pest management technologies are being developed with farmers using a participatory approach.