1. Changes in serum triglyceride and high density lipoprotein (HDL) cholesterol after a fatty meal have been studied in smokers and non-smokers.
2. Average serum triglyceride during the study was higher in smokers than in non-smokers.
3. In non-smokers there was a rise in the HDL2/HDL3 cholesterol ratio after oral fat, but not in smokers.
4. These findings are compatible with the hypothesis that smoking interferes with the lipolysis of triglyceride rich lipoproteins and the conversion of HDL3 into HDL2.