Variable prevalence rates of damselfish neurofibromatosis (DNF) between Florida Keys reefs have previously been used as evidence against a genetic etiology of DNF in favor of an infectious etiology. Such a conclusion also presumes a genetically homogeneous population, that is, panmixia, throughout the reef system population. In order to address this issue, we conducted a survey of allozyme variation in two closely situated populations of the bicolor damselfish (Pomacentrus partitus) within the Florida Keys. The results suggest that gene flow between these two populations is restricted. Data analyses show significant heterogeneity in allelic frequencies at two enzyme-coding loci (ACO1 and ADH) and a relatively high estimate of genetic distance between samples from Little Grecian Rocks Reef and Grecian Rocks Reef. These preliminary findings are consistent with the hypothesis that the etiology of DNF is genetic. It is of some interest that these results are in contrast to previous studies of genetic differentiation among widely separated populations of coral reef fishes. Sufficient allozyme variation was detected (12 out of 23 loci were polymorphic) to allow for a subsequent rigorous assessment of panmixia in these populations at risk for DNF.