Serum cholesterol and triglyceride levels were determined in 17 children with various forms of anaemia and varying rates of red cell production. Anaemic patients had low serum cholesterol values, and a good correlation between Hb and serum cholesterol levels was found. The serum triglyceride levels were also low in most patients, but the results were less closely related to Hb. No relationship could be demonstrated between the rate of red cell production as judged by reticulocyte counts, and serum cholesterol or triglycerides. Apparently all lipoprotein classes are reduced in individuals with uncomplicated anaemias. This hypolipidaemia can only partly be explained by the diluting effect of the increase in plasma volume accompanying anaemia.