To the Editor: Burke et al. (April 4 issue)1 claim that blood cholesterol levels decreased significantly in the Twin Cities between 1980–1982 and 1985–1987, attributing the decrease to both changes in lifestyle and intervention by physicians. Total cholesterol levels decreased 2.4 percent in men and 3.0 percent in women during that interval. There is no mention of whether the subjects' blood was drawn at a particular time during the year or throughout the year. There is a cyclic, seasonal variation of 3 percent in total cholesterol levels in North America, the levels being higher in the winter than the summer.