Abstract Heparin was administered to dogs by inhalation, directly into jejunal fistulas and by intravenous injection. Anesthetized rabbits received heparin sublingually and intravenously. Human volunteer subjects received heparin or a combination of heparin and EDTA sublingually and rectally and heparin alone as the sodium or potassium salts by inhalation. Volunteer subjects received heparin buccally or a placebo together with a high fat meal in a cross-over experiment. Lipemia clearing activities as well as various blood lipid levels were measured before and at intervals after administration of the drug. Compared with the changes following parenteral heparin therapy, no significant effects were seen after the administration of heparin by routes other than injection. The addition of EDTA to heparin did not significantly improve absorption when given to volunteer subjects sublingually or rectally. Those given heparin by inhalation absorbed neither the sodium salt nor the potassium salt in detectable quantities. Ingestion of a standard fat meal containing 71 gm. of neutral fat, however, brought about increases in serum triglyceride levels, lipoprotein values S f 20–400, chylomicrons measured as turbidity and total lipid levels. Buccal administration of heparin shortly after the standard fat meal had no influence on the serum lipid levels.