The acetone extract of the whole plant of Plectranthus grandidentatus provided the already known abietanes royleanone, 6,7-dehydroroyleanone, horminone, 6 beta-hydroxyroyleanone, 7 alpha-acetoxy-6 beta-hydroxyroyleanone and the abietane dimers grandidone C, grandidone D and 7-epigrandidone D, together with a mixture of fatty acid esters of 7 alpha-acyloxy-6 beta,12-dihydroxy-abieta-8,12-diene-11,14-dione. Some of these compounds showed moderate antibacterial activity. Copyright (C) 1996 Elsevier Science Ltd