CD36 is an 88-kDa glycoprotein expressed on platelets and monocyte/macrophages (M phi). CD36 is a multifunctional receptor for collagen, thrombospondin, oxidized low density lipoproteins (LDL), and long-chain fatty acids. The present study was performed to investigate whether CD36 can function as an adhesion molecule which is involved in mediating human macrophages (M phi) adhesion to type I collagen in vitro. The M phi of human CD36-deficient as well as normal control subjects were isolated and cultured on the multi-well plates coated with type I collagen, a natural ligand for CD36. Up to 2 h of incubation, the M phi from CD36-deficient patients showed almost a similar to 55% decrease in adhesion to type I collagen in comparison to those from controls (P < 0.01). However, there was no significant difference in the adhesion thereafter. Furthermore, the addition of antibody against CD36 into the media of control M significantly inhibited the adhesion by similar to 50% (P < 0.05). The addition of oxidized LDL (OxLDL) did not alter adhesion of M from both CD36-deficient and controls. These data suggest that CD36 is involved in the adhesion of M phi to type I collagen, especially in the early stage of adhesion.