OBJECTIVE Investigating the expression of Bax, Bcl-2 and Caspase-3 in dorsal root ganglion after partial dorsal root rhizotomy in spared root. METHODS Adult cats were used. The study comprised a normal control group (n=5) and three expriment groups (n=5 per group). The unilateral root rhizotomy was performed on the 15 cats of the 3 experiment groups. On the 3rd, 7th and 14th days after partial dorsal rhizotomy, the DRG (L6) of 5 cats per batch were taken and made into frozen sections and were stained under the same condition using specific Bax, Bcl-2 and Caspase-3 antibody by ABC method. The Bax, Bcl-2 and Caspase-3 positive large-, medium- and small-sized neurons in DRG were counted in the 3 experiment groups and in the normal control group. RESULTS In the intact animals of the normal control group, the Bax, Bcl-2 and Caspase-3 immunoreactants were mainly distributed in medium, small neurons and a few large neurons. The number of Bax positive neurons in spared DRG of the 3rd day group increased apparently as compared with that of the normal control group but decreased apparently in the 14th day group and showed no significant difference when compared versus control (P>0.05). There was no significant difference between the 14th day group and normal control group. Bcl-2 expression in spared DRG displayed no difference among the four groups. The number of Caspase-3 positive neurons in spared DRG of the 3rd day group increased apparently when compared against control (P<0.05), but it was not significantly different from that of the 7th day and 14th day groups (P>0.05). CONCLUSION Partial dorsal root rhizotomy mainly has an effect on the expressions of Bax, Bcl-2 and Caspase-3 in medium- and small-sized neurons of spared DRG, the peaks of the expressions may appear 3-7 d after the operation.