A single population of the iguanid lizard, Sceloporus grammicus, was found to have fission polymorphisms in three of four metacentric macrochromosome pairs. This variation resulted in eight different karyotypes in a sample of 24 lizards. Of these 24 lizards, 7 were single heterozygotes, 11 were double heterozygotes, and 1 was a triple heterozygote. Meiotic analyses of males heterozygous for different combinations of fissions indicated completely normal disjunction and production of chromosomally balanced gametes. The polymorphisms in this population did not appear to deviate strongly from Hardy-Weinberg equilibrium. There was no evidence of selection against chromosomal heterozygotes in this population.