It has been characterized earlier that bovine gingival lipids contain a fairly high level of arachidonic acid, a potential precursor of prostaglandin biosynthesis. The purpose of the present study was to investigate whether prostaglandins are natural components of bovine gingival tissues. Qualitative analysis of the lipid extract by a combination of thin-layer chromatography on plain and silver nitrate-impregnated silical gel plates and ultraviolet absorption spectroscopy strongly indicate the presence of PGE1, PGE2, and PGF2. There was also an indication for the occurrence of other prostaglandins, such as PGB, PGE3, PGF1, and PGF3.