Abstract: Tripterine is one of the components isolated from Tripterygium wilfordii Hook. Previous studies demonstrated that tripterine inhibited not only humoral and cellular immune responses but also some inflammatory responses. The present investigation attempted to observe effect of the drug on productions of IL-1 from macrophages, IL- 2 from splenocytes and PGE₂ from synovial cells. The results showed that tripterine (0. 1 ～ 1.0μg/ml )significantly inhibited IL-1 activity of murine peritoneal macrophages induced by LPS. Because both intracellular and extracellular IL- 1 activities were decreased, so tripterine might be able to reduce the production and release of IL- 1. Besides, inhibiton of IL-1 production was observed when macrophages were pretreated with the drug for 8 h and 16 h. A good relationship was found between the effect and concentration of tripterine which inhibited IL-2 production from ConA-activated murine splenocytes. Kinetic study indicated that IL- 2 production was decreased when splenocytes were pretreated with the drug for 3 h, 6h and 12 h. Synovial cells obtained from rabbit knee joint were cultured successfully. A23187 was found to augment PGE₂ synthesis modestly. Tripterine significantly reduced PGE₂ release from synovial cells in a concentration dependent manner.