An examination of the electrophoretically detectable allelic variation of 24 enzymes and 8 structural proteins in spotted seatrout (Cynoscion nebulosus) from four localities on the Texas Gulf coast resulted in scorable phenotypes for 44 putative gene loci. Levels of genetic variability found were less than that reported for other marine teleosts. Polymorphic loci per population ranged from 9.0 to 13.6% and average individual heterozygosity for all loci ranged from 0.7 to 1.9%. F-statistics suggested a low degree of differentiation into subpopulations with a mean Fst of 0.009. Although genetic similarities between the four locations were relatively high, averaging 0.973, some differentiation of the genome was demonstrated via cluster analysis of Roger's genetic similarity estimates. A geographic cline in the frequency of the Aat-1^80 allele and in average individual heterozygosity as a function of degrees west longitude was observed. Spotted seatrout inhabiting the Texas Gulf coast can be described as possessing low levels of genetic variation and little differentiation into subpopulations.