The quality and viability of cowpea seed were influenced both by season of harvest and seedcoat type. The wetness that accompanies harvest in the first part of the growing season in southern Nigeria greatly reduced quality and viability of seeds with wrinkled testa but had a less deleterious effect on smooth ones. Quality reduction in the form of mouldiness was due primarily to invasion by Fusarium equiseti, which, together with a Pseudomonas sp., was also responsible for viability loss. Smooth seeds were more resistant to both organisms than the wrinkled ones. Seeds of both seedcoat types were free of mouldiness and bacterial infection when harvested in the dry season. Viability scores of seeds of very high or very low quality were independent of the method of testing but those of apparently clean wrinkled seeds harvested in the wet season varied according to the method of testing.