This study was conducted at the International Center for Textile Research and Development, Texas Tech University, Lubbock, Texas on four Egyptian cotton varieties (Giza 45, Giza 70, Giza 77 and Giza 75) and two US cotton ELS varieties (Pima S7 and Pima S6) as well as four Upland varieties (Paymaster HS-26, GB 3744, DPL Acala 90 and DES 119) to compare the different length measurements and distributions produced by HVI, Fibrograph, AFIS, Peyer 101 and Suter Webb from these long, medium and short staple varieties. The results showed considerable differences between length measurements obtained from different instruments, such differences appeared to be affected by cotton variety with reference to its length. Simple correlation coefficients between length uniformity, length variation (CV%) and short fiber content measurements were also calculated.