N-glycans of human Fcgamma receptor III (FcgammaR III) are believed to be involved in the interaction with complement receptor type 3 (CR3) (Sehgal et al. [1993] J. Immunol., 150, 4571-4580). Recombinant human soluble FcgammaRIII (rhsFcgammaRIII), which is produced in baby hamster kidney (BHK) cells, has been shown to interact with CR3 in a manner similar to native FcgammaRIII. We elucidated the N-glycosylation profiles of rhsFcgammaRIII by the 3D high-performance liquid chromatography mapping technique. It was revealed that the N-glycans of rhsFcgammaRIII are much more divergent (consisting of 20 neutral, 7 monosialyl, 4 disialyl, 5 trisialyl, and 1 tetrasialyl oligosaccharides) than those previously determined for BHK-expressed mouse sFcgammaRII, notwithstanding close structural similarity of polypeptide chains between the two sFcgammaRs. Particularly, high-mannose type oligosaccharides are specifically expressed on rhsFcgammaRIII.