Purified and unstained nuclei were isolated from the leaves of several Gossypium species (diploid and tetraploid) by means of a citrate buffer (pH 5.0), Triton X-100 (5%), and a reducing sugar (1M glucose). DNA, previously unobtainable, was then extracted from the nuclei by conventional means. Comparisons of final DNA yield were made between three methods of purification: namely, the standardized ribonuclease procedure, hydroxyapatite chromatography and equilibrium density centrifugation in cesium chloride. The latter method produce the lowest, yet purest, yield of DNA for renaturation studies in Gossypium.