Relatively high concentrations of the triterpane homologous series, namely, 17 alpha(H), 21 beta(H)-diahopanes, are found in crude oils. Possible routes of their formation are discussed. As shown by the gas-liquid chromatographic analysis of crude oils with an unusual triterpane distribution, they have increased relative concentrations of neoadiantane and high-molecular-mass n-alkanes and practically do not exhibit the unresolved (naphthenoaromatic) hump in the chromatogram. It is assumed that 17 alpha(H), 21 beta(H)-diahopane and its homologues are of bacterial origin.