The second taurine-containing lipid (taurolipid B) was found in cells of Tetrahymena thermophila. The lipid accounted for about 1.4% of the total lipids of the cells. The lipid was subjected to mild alkaline and methanolic hydrochloric acid hydrolyses, and the structures of the hydrolysis products were identified by mass and nuclear magnetic resonance spectrometry, as taurine, 2,3,7,13-tetrahydroxystearic acid and non-hydroxy fatty acids. By spin-decoupling analysis in nuclear magnetic resonance spectrometry, the structure of the taurolipid B was identified as 2-(3-acyloxy-2,7,13-trihydroxyoctadecanoyl)aminoethane sulfonic acid. This structure shows that taurolipid B is a homologue of the first taurine-containing lipid (taurolipid A).