We determined the concentrations of RNA and DNA in white muscle of rainbow troutOncorhynchus mykissand fathead minnowPimephales promelasthat had been frozen in either liquid nitrogen, a lowtemperature freezer (–80°C), or a household freezer (–20°C), or had been left 1–24 h after death in either wet ice or cold water (8.5–9.5°C). Both RNA and DNA were resistant to enzymatic breakdown because their concentrations and the RNA:DNA ratio did not differ significantly among treatments in either species. However, there was a tendency for muscle DNA concentration to decrease in fathead minnow stored in water for 24 h. Paired samples of rainbow trout muscle, both of which were frozen in liquid nitrogen but one of which was thawed and refrozen before analysis, differed significantly in DNA concentration and RNA:DNA ratio. The refrozen samples had significantly lower DNA concentrations, which led to significantly higher RNA: DNA ratios.