<jats:p>In the males of the ant F. polyctena 38 different fluorescentic substances were isolated by paper column chromatography. Nine of them could be identifed as isoxanthopterin, pterin-6-carbonic acid, ʟ-6- (erythro-1,2-dihydroxypropyl) -pterin, D-or-L-6- (threo-1′,2′,3′-trihydroxypropyl) -pterin, lumacine, lumacine-6-carbonic acid, isoxantholumacine, 6-methyl-8-ribityl-isoxantholumacine and riboflavin. Some of these pteridines and also riboflavin were bound in different relations. The isolated compounds are characterised by UV spectra, Rf values, electrophoretic mobility, and some oxidative or reductive reactions. The importance and formation of some photoactive compounds are discussed.