The effect of collagen hydrolysates from fish skins on lipid profile was assessed in rats administered chum salmon or rainbow trout collagen peptide. Single oral administration of soybean oil with or without one of either type of fish collagen peptide demonstrated that rat plasma triglycerides were significantly decreased 2 h later after the intake of oil and peptide mixtures (p < 0.05). The free and peptide forms of hydroxyproline derived from fish collagen peptides were statistically higher than those of zero time after oral administration. To test the effect of fish collagen peptides on continuous administration, rats were fed an AIN-93G purified diet containing 0.17% fish collagen peptide. The peptide groups had lower levels of plasma total lipids and triglycerides compared with the control group. However, the body, liver, and fat weights of rats were not significantly different between groups. These results suggest that fish collagen hydrolysates affect lipid absorption and metabolism in rats and may be useful in suppressing the transient increase of plasma triglycerides.