The effects of growth hormones and nutrients on growth and alkaloid production in callus cultures of Uncaria rhynchophylla (MIQ.) MIQUEL (Rubiaceae) were investigated. Gamborg B5 (B5) medium supplemented with indoleacetic acid (10-4 M) and 6-benzylaminopurine (3×10-5 M) was optimized both for the growth (1.8 g fresh weight/5 weeks) and alkaloid production (1.73 mg/g dry weight/5 weeks). The influence of sucrose concentration was examined, and 2% sucrose was found to be the most appropriate for the growth and alkaloid production. The effect of the composition of nitrogen sources was examined. Maximal growth and alkaloid production were obtained when 6 mM ammonium chloride and 25 mM potassium nitrate were added to the B5 medium. Hirsuteine, hirsutine, 3α-dihydrocadambine and ursolic acid were isolated from the callus. The 3α-dihydrocadambine concentration of callus was ca. 50-fold higher than that of the hooks and stems of U. rhynchophylla.