Hypocotyls of seedlings of four cotton cultivars (Auburn M, Coker 310, Delco-277J, and Dixie King 3) were inoculated with Pythium ultimum. Selected plants were grown to maturity, self pollinated, and progenies were evaluated for disease for disease susceptibility. Variation in hypocotyl symptom expression among the four cultivars. Variation among seedlings of Auburn M was not reduced significantly among, progenies through three successive generations of selection and self-pollination. A small but significant difference in susceptibility between Delcot 277J and Coker 310 was established. This difference was apparent in the parent seedlings, and in two succeeding generations of selection and self-pollination of resistant plants. Improvement in resistance was demonstrated with progenies of Auburn M. Third generation seedlings were obtained that were significantly more resistant than the Auburn M cultivar parent.