To maintain embryogenic cell lines of Pimpinella brachycarpa, we suspension-cultured friable and vapidly growing yellowish calli in an MS liquid medium containing 0.2 $mu$M 2,4-D and 0.5 $mu$M BAP. Efficient somatic embryogenesis was achieved when selected tells were then transferred to an MS medium (0.2% gelrite) that contained 0.2 $mu$M 2,4-D, 0.5 $mu$M BAP and 10.0 $mu$M TDZ (thidiazuron). These cells were cultured at 27$^{circ}C$ under continuous illumination (21.5 $mu$E m$^{-2}$ /s$^{-1}$ ). Embryogenic calli expanded about four-fold, and developed into pale yellow calli. Somatic embryogenesis was initiated only from glossy and nodular-type calli. After two more weeks of culture, globular embryos appeared on the surface of calli grown in the MS medium that contained 10.0 $mu$M TDZ only or in combination with 0.5 $mu$M NAA. Experimenting with 2,4-D, an auxin, to promote embryogenic calli resulted in excessive browning and death. We overcame this problem by growing glossy embryogenic and nodular calli on media that contained 10.0 $mu$M TDZ. Calli that were not treated with TDI turned dark brown and were not viable. Up to 14% of th2 calli showed somatic embryos when the medium was supplemented with 10.0 $mu$M TDZ and 0.5 $mu$M NAA. Embryos from these TDZ-induced, somatic embryogenic calli grew efficiently forming multiple shoots and developing into normal plants. Therefore, efficient differentiation of suspension-cultured tell clusters into embryogenic calli, along with treatment of subsequent somatic embryos by TDZ, suggests that TDZ probably helps in establishing the optimum cytokinin-auxin ratio required for induction and expression of somatic embryogenesis.