Twenty-one transgenic genotypes of Upland cotton, including the 15 most widely planted transgenic cultivars in 1998 and their nontransgenic parents, were evaluated under growth chamber conditions for resistance to the nematodes Meloidogyne incognita (root-knot nematode) and Rotylenchulus reniformis (reniform nematode). The highly M. incognita-resistant breeding line Auburn 623 RNR, the M. incognita-resistant cultivar Stoneville LA887, and the susceptible obsolete cultivar Deltapine 16 were included as controls. No important decrease in nematode reproduction was attributable to any transgene in any cultivar. Some other differences in nematode reproduction, however, were apparent. R. reniformis reproduction was prolific on all cultivars and on eight significantly exceeded Deltapine 16. In contrast, 10 cultivars exhibited M. incognita gall ratings and/or egg densities on roots significantly lower than on Deltapine 16. Six Stoneville breeding lines (experimental transgenics) had levels of M. incognita root galling and reproduction comparable to Stoneville LA887.