The progress of rigor-mortis was followed together with ATP degradation and lactate accumulation during storage at 0 and 10°C of sardine and mackerel spiked at the brain. Both sardine and mackerel showed rapid progress of rigor-mortis, attaining a full-rigor state at a few hours after death. Although rigor-mortis exhibited a large individual variation, its rate was apparently slower with samples stored at 10°C than with those stored at 0°C for both species. ATP and lactate concentrations in sardine muscle were relatively constant a few hours after death irrespective of the storage temperature, in contrast with rigor-mortis progress. Therefore, many sardine samples exhibited a high rate of rigor-mortis even when they maintained a high concentration of ATP, especially with those stored at 0°C. Mackerel gave rise to a more reasonable relationship between rigor-mortis progress and ATP degradation than did sardine. Correlation of ATP content with that of lactate did not markedly differ from each other between samples stored at 0 and 10°C and was calculated to be around r=-0.8 for both sardine and mackerel. It was noted that sardine and mackerel relaxed from a rigor-state at a few hours after spiking when stored at 10°C.