Technical Abstract: The lack of genetic diversity in the cotton crop may be recognized as a potential threat to genetic vulnerability and to sustaining high yields. Ten Gossypium hirsutum and ten G. Barbadense improved germplasm have been assayed with 217 molecular markers (SR). Marker percent difference within G. Hirsutum species ranged from 10 up to 40%. However, the diversity accounted by region, e.g., within Acala and within Delta cottons, was approximately 18%. Marker percent difference within G. Barbadense ranged from 8 up to 45%. Within the Pima PS series (1, 4, 6, 7, & 32), the lowest percent difference was between PS4 and PS32, and was around 37%. Marker percent difference confirms the existing narrow genetic variability previously reported from traditional genetic studies within G. Hirsutum species, and the same trend is observed for the G. Barbadense species. The necessity of introgression of favorable alleles into a wider range of germplasm exists to ensure genetic diversity.