The relatively short fibers of many varieties of cotton (Gossypium hirsutum L.) adapted to Texas limit the profitability and utilization of cotton in this state. Two M₅ lines (TTU 202-1107-B and TTU 271-2155-C) selected for improved fiber length were crossed with two cultivars (Explorer and SC 9023) adapted to the Texas High Plains. The parents, F₁ and F₂ of each cross were grown at Lubbock, TX in 1999 and fiber from individual plants harvested. Duplicate estimates of fiber length were determined using High Volume Instrument (HVI) analyses. Despite adverse environmental conditions during fiber elongation in 1999, the mutant lines had an average fiber length 0.14 inches (3.5 mm) longer than the adapted cultivars. An average of 29.5% of the individual plants of the four F₂ populations had fiber length that exceeded 1.19 inches (30.2 mm). All four F₂ populations had significant, positive correlations between fiber length and fiber strength r = 0.34 ** to r = 0.61 **). These results indicate that TTU 202-1107-B and TTU 271-2155-C could be useful germplasm to improve fiber length of commercial cotton cultivars adapted to short growing season areas.