OBJECTIVE Investigating the expression of glial cell line-derived neurotrophic factor (GDNF) in dorsal root ganglion after partial dorsal root rhizotomy and acupuncture in spared root. METHODS Fifteen adult cats were divided into three groups. Two groups were subjected to unilateral spared root rhizotomy (L1-L5, L7-S2 DRGs were sectioned, L6 DRG was spared). In one of these operating groups, two sets of acupoints (Zusanli and Xuanzhong; Futu and Sanyinjiao) located in the distribution area of spinal nerve L6 were electro-stimulated alternatively 30 min everyday by electro-needling. The other operation group was not treated with acupuncture. On the 7th day after partial dorsal rhizotomy and acupuncture, the animals of these two groups and another group (intact animals as reference group) were sacrificed. The DRGs (L6) were taken and made into frozen sections and were stained under the same condition using specific GDNF antibody (1:1000) by ABC method. The GDNF positive large, medium and small sized neurons in DRG were counted. RESULTS In intact animals, about 55% neurons, including large sized neurons (25%) and a few small (16%) and medium sized neurons (14%), were stained. In contrast, at 7 days after partial dorsal root rhizotomy, the numbers of positive neurons decreased greatly (35%) more than that of reference group (P < 0.05). However, following acupuncture, about 90% neurons, including large (28%) medium (17%) and small (45%) neurons, came to be stained again. CONCLUSIONS The number of GDNF positive large neurons decreased greatly at 7 days following partial dorsal root rhizotomy, but increased greatly after acupuncture. In addition, the number of GDNF positive small neurons increased greatly after acupuncture (P < 0.05).