Fungicides used commercially for control of cotton seedling diseases were evaluated under field conditions over a 2-year period for their effects on the prevalence and incidence of the entomopathogenic fungus Neozygites fresenii (Nowakowski) Batko, in the cotton aphid, Aphis gossyppii Glover. Carboxin and etridiazole significantly reduced N. fresenii prevalence during early season in the first year of this study. All fungicides tested, particularly carboxin, enhanced N. fresenii prevalence in late season during both years of this study. However, the enhanced prevalence did not result in a simultaneous increase in A. gossypii control. Biological and cultural implications are discussed.