The levels of plasmatic lipids and the lipo and apoprotein composition of lipoprotein of high density were analysed in 18 patients, diagnosed as having non-insulin dependent diabetes, and compared to a control group of 18 healthy patients. 10 patients showed a moderate hypertriglyceridemia, this sub-group having the main HDL alteration. In this lipoprotein fraction an increase of triglycerides was observed, and a decrease in cholesterol and apoprotein III, probably as result of a lower activity of lipoprotein lipase in plasma.