A hybrid between S. morelliforme and S. clarum, both diploid (2n = 2x = 24) tuberous Solanum spp. was heterozygous for a chromosome interchange and possibly 2 inversions. These changes were also followed in F2 plants. In addition either normal or transgressive segregations were found for 3 morphological and 5 biochemical characters. As this is the first demonstration of gross differences in chromosome structure between individuals of different tuberous Solanum spp. the possible causes for the absence of such difference in this group are discussed.