Two continuous human glioma derived cell lines, LI and DF, were established in our laboratory. Both cell lines showed cytological features and in vitro behavior similar to those of the respective original neoplasms. These two lines were characterized for their main biological properties including in vitro and in vivo growth rate, clonogenic ability and tumorigenicity in nude mice. The plating efficiencies were generally high both during exponential and stationary growth phases and a high tumorigenicity was observed. All injected nude mice developed tumors. The two lines were tested for chemosensitivity to 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) and cis-Diamminedichloroplatinum II (DDP). Heterogeneity in biological features and in drug sensitivity was observed. Exposure of the two lines to BCNU and DDP showed that the glioblastoma (LI) was less sensitive than the anaplastic astrocytoma (DF). For both lines BCNU was more effective on cells in plateau than in exponential phase, while the killing effect of DDP was not phase-dependent.