Survival in 3 Hyla versicolor and 2 H. chrysoscelis control crosses was studied in USA populations. Survivorship in H. versicolor controls was considerably lower than survivorship in H. chrysoscelis at all stages; and survivorship in the Texas .times. South Carolina H. chrysoscelis cross exceeded survivorship in the Texas .times. Texas H. chrysoscelis cross. A comparison of mean mortality at 2 wk after hatch in H. versicolor controls and other hylid controls is given. Mean mortality in H. versicolor controls is significantly higher than mean mortality in H. chrysoscelis controls. The difference between mean mortality in H. versicolor controls and mean mortality in other hylid controls was tested statistically. Depending on the genotypes of the parents, in many H. versicolor control crosses a significant proportion of the progeny would contain 3 or possibly 4 mutant alleles, thus leading to decreased viability. H. versicolor may be carrying a form of genetic load as a result of tetraploidy. This type of load does not fit strictly within current definitions of mutational load (Wallace, 1970), and perhaps a new category may be needed for polyploid organisms. The results of hybrid crosses involving H. versicolor are tabulated. Compatibilities of H. versicolor and H. chrysoscelis with each other and with species to which both have been crossed are given. The tetraploid H. versicolor forms quadrivalents during the 1st meiotic metaphase, while the diploid H. chrysoscelis forms normal bivalents. The formation of bivalents in a polyploid indicates that the polyploid is either an allopolyploid or a relatively old autopolyploid that has begun the process of diploidization. H. versicolor may have already begun functional diploidization although quadrivalents are still formed. The poor viability of H. versicolor .times. H. chrysoscelis F1 could be ascribable to triple doses of each gene and consequent genetic imbalance.