The dietary effects of two high protein diets from two species of sea urchin (Paracentrotus lividus and Echinus esculentus) as compared to a reference protein such as casein on serum lipid levels and on intestinal disaccharidases and alkaline phosphatase were studied. After 23 days, the containing the two sea urchins as diets compared to casein decreased the cholesterol level and significantly increased the HDL-cholesterol in serum. The consumption of Echinus esculentus meal produced a significant decrease in lactase activity. The intestinal alkaline phosphatase activity increased not significantly in animals fed on the sea urchin meal.