Abstract： AIM To study the different effects of glial-de-rived neurotrophicfactor( GDNF) on injured dosal root ganglion(DRG) neurons using injurious model of neurons induced by kainic acid in vitro, so as to provide new thoughts for studying functional mechanism, expression pattern, and bioassay methods of GDNF. METHODS Primarily cultured DRG neurons were dissected from neonatal rats in N1 serum-free medium,and then kainic acid medium was added into cultures at the final concentration of 5 μmol.L-1 and incubated for 6～8 h . The next step was performed to culture in DF12 serum-free medium supplemented with GDNF for 24 h. Eventually, MTT was used to test viability of cells by value. Trypan blue staining cell count and total protein of neurons were determined. DRG neurons were observed to detect the neurite length. RESULTS ① A values for viability of cells : GDNF+KA (0.0328±0.006);KA (0.0285±0.0075); GDNF (0.0398±0.002); Blank (0.041±0.002). ② Cell count: GDNF+KA (60±4.4); KA (35.7±2.2); GDNF (59.3±3.6); Blank (57.7±2.9). ③ Total protein of cells GDNF+KA (70.3±9.2); KA (49±3.7); GDNF (75±7.3); Blank (68±5.5)(P<0.05; P<0.01). ④ Neurite length: Remarkable differences existed neither between experimental groups and control groups, nor between GDNF groups and Blank. CONCLUSION GDNF has no distinct effects on DRG neurons in normal serum-free condition in vitro, whereas it significantly promotes viability, survival, sythesis of total protein of DRG neurons after kainic acid- induced injury. No remarkable promotions occur to outgrowth of neurite.