Delayed emergence, increased seedling disease, and reduced stands are documented effects of low cotton seed quality. We evaluated the effects of reduced cottonseed quality in the absence of stand variation for early and late field plantings in 1986 and 1987. Seed quality was reduced using the hot water method of deteriorating seed. Planting rates increased in proportion of degree of seed deterioration. After final stands were established, seedlings were randomly thinned to uniform densities. A slight decrease in plant height and a trend toward reduced yields were associated with deteriorated seed. These results suggest that the major adverse effects of seed deterioration are related to low stand density and to interplant competition due to non-uniform stands.