The four Egyptian cotton varieties; Giza 80, Giza 73, Giza 66 and Dend.ra and the two Upland cotton varieties, i.e., McNaire 220 and Stoneville 213 were grown on two diffe rent sowing dates, i.e.. 26th of Harcn and 24th of Hay in 1981 and 1982 seasons at Giza Experjirental and Research Station. Results indicated that seedeotton yield (SCY) and lint yield (LY) were almost increased by early sowing. Early sowing date encouraged production of more boll per square meter (a/&), more bol], per plant (B/P) and higher lint percent LP. Differences were also evident with respect to fiber properties. Differences were significant for 12.5% SL, mean length, riicronaire and yarn strength between the two sowing dates. Significant genotype x date interaction was encountered as to seed per boll (S/B), (LP), Mean length (ML), 12.5% SL, micronajre and hair weight. Genotypes differed in their stability of performance in that th. Egyptian varieties were more stable than their Upland counterparts.