Sudan Black B contains two blue main components, SSB-I and SSB-II. Their chemical structures were determinated by the aid of two-dimensional thin-layer chromatography, column chromatography, absorption, IR, mass, H1-NMR, and C13-NMR spectroscopy and were proved by alternate synthesis. SSB-I has been found to be 2,3-dihydro-2,2-dimethyl4-[(4-phenylazo-1-naphthalenyl)-azol]-1H-perimidine. For SSB-II was confirmed the known structure 2,3-dihydro-2,2-dimethyl-6-[(4-phenylazo-1-naphthalenyl)-azo]-1H-permidine. Relations of chemical structure of SSB-I and SSB-II to their staining properties are discussed.