Background: Obesity is a pathological state caused by abnormal or excessive accumulation of fat. Swietenia mahogani JACQ., known as West Indian mahogany, is a medium-sized semi-evergreen tree belonging to Meliaceae. Their seeds are used in Indonesian folk medicine as a treatment for hypertension, diabetes, malaria, and it also has anti-feedant activities. The major components of S. mahogani are B, D-seco limonoids, a type of irregular triterpenes are well known. Objective: We tried to find the bioactive components, which have the inhibitory activity on adipocyte differentiation from the seeds of S. mahogani. Material and Methods: 3T3-L1 cells, derived from mouse preadipocyte, are widely used in studying adipogenesis process. In this study, we used 3T3-L1 cells to find natural products with the inhibitory activity on adipocyte differentiation. S. mahogani seeds were dried and extracted with 100% MeOH. Results: The methanolic extract was fractionated by bioassay-guided method to give nine B, D-seco limonoids (1-9) with slight structural modifications. Among nine compounds, compounds 4, 6 and 8 exhibited significant inhibitory effects of cell differentiation on 3T3-L1 cells. Those compounds have tigloyl residue at C-3 in common. Besides, compounds with no tigloyl residue at C-3 showed insignificant effect. Nevertheless, not all compounds with tigloyl residue at C-3 exerted significant inhibitory effect. Conclusion: These results suggested that tigloyl residue at C-3 may play a role in the anti-proliferative activity on a dipogenesis and the refined extract of S. mahogani may have a potential to be developed as a therapeutic agent to treat obesity.