Three putative mutant upland cotton (Gossypium hirsutum L.) germplasm lines, TAM 94L-25-M24, (Reg. No. GP-952, PI 664553), TAM 94L-25-M25 (Reg. No. GP-953, PI 664554), and TAM 94L-25-M30 (Reg. No. GP-954, PI 664555), were developed by the Cotton Improvement Laboratory, Department of Soil and Crop Sciences, Texas AgriLife Research and released in 2010. These lines were developed by treating the parent germplasm line, TAM 94L-25 (PI 631440), an upland cotton line with improved high-volume instrument (HVI) upper-half mean length (UHML), with the chemical mutagen ethyl methanesulfonate. TAM 94L-25-M24, TAM 94L-25-M25, and TAM 94L-25-M30 exhibited UHML and fiber bundle tenacity that exceeded that of the parent, TAM 94L-25. These three lines yielded as much or more than the M 0 parent and exhibited other HVI fiber-quality parameters that were within acceptable ranges. TAM 94L-25-M24, TAM 94L-25-M25, and TAM 94L-25-M30 should be useful in creating cultivars with improved fiber length and strength.