Several lanostane triterpenes [butyl ganoderate A (1), butyl ganoderate B (2), butyl lucidenate N (3), and butyl lucidenate A (4)] bearing a butyl ester side chain from the fruiting bodies of Ganoderma lucidum exhibited considerable inhibitory effects on adipogenesis in 3T3-L1 cells. The inhibitory mechanism of 1 and 3 on adipogenesis in 3T3-L1 cells was investigated; we found that the mRNA and protein expression levels of SREBP-1c were reduced by treatment with 1 and 3 versus the untreated control. Furthermore, compounds 1 and 3 suppressed the mRNA expression levels of FAS and ACC. These results demonstrate that inhibition of adipogenesis in 3T3-L1 cells by treatment with 1 and 3 may be mediated in part through down-regulation of the adipogenic transcription factor SREBP-1c and its target genes, such as FAS and ACC.