Male 21-d-old Wistar rats were fed over 3 experimental periods. During the first period of 4 wk, diets contained 10% casein or defatted soy flour proteins, with or without 0.5, 1, 2 or 3% sodium alginate or sodium carrageenan, and were heated. During the second period, they were fed a standard diet for 16 wk with 17% proteins, and during the third period, they received the same diet as in the first period, but with 20% proteins. Rat body weights were measured throughout the study period; plasma lipid levels were then determined after fasting. Presence of sodium alginate in the diet had no effect on growth, but rats fed carrageenan presented growth retardation at the end of the experimental period, which was not altered by refeeding the standard diet. Sodium alginate did not modify rat triglyceridemia, except at the 1% level. Carrageenan had a hypotriglyceridemic effect. Alginate and carrageenan had no effect on blood cholesterol. Compared to soybean protein, casein intake did not increase plasma cholesterol levels as generally described. The effect of carrageenans on growth and plasma triglyceride levels could be a result of their physico-chemical properties.