We have examined karyotypes from thirteen species of the North American cyprinid genus Notropis: N. chrysocephalus, N. fumeus, N. longirostris, N. lutrensis, N. oxyrhynchus, N. roseipinnis, N. sabinae, N. shumardi, N. signipinnis, N. texanus, N. umbratilis, N. venustus, and N. volucellus. All thirteen species have 2n=50 chromosomes. Estimated haploid arm numbers among the thirteen species ranged from 46-50; one-armed chromosomes (centromeres subterminal to terminal) comprised only a small portion of the karyotype of each species. Chromosomal evolution in Notropis, and in North American Cyprinidae, has been remarkably conservative. Almost all species karyotyped have 2n=50 chromosomes, and with one exception, cyprinid species with 50 chromosomes vary in estimated haploid chromosome arm number from only 46-50. In contrast, speciation in these fishes appears to have been rapid. Thus, the present data suggest that gross chromosomal rearrangement has played only a very minor role in the speciation and evolution of these fishes.