Objective To study the roles of spermidine and spermine in affecting antizyme expression in early regenerating rat liver. Methods Adult male SD rats were surgically rendered partial hepatectomy via a modification of a procedure reported by Higgins and colleagues (1931), then they were treated with different dosages of exogenous polyamines (dissolved in 0.9% NaCl) s.c. Antizyme (AZ) gene transcription and protein expression in regenerating liver were evaluated by using the RT-PCR and Western blotting assay respectively. Results In intact liver (0 hour after partial hepatectomy) of the control group, the levels of AZ mRNA transcription and protein expression were very low. In regenerating liver induced by partial hepatectomy, AZ mRNA content and protein expression increased quickly, peaked at 3 hours, followed by significant decreases at 5 hours, afterwards, it reached another peak at 7 hours, and then decreased gradually. In rats administered with different doses of spermidine and spermine, the change tendency of AZ mRNA level and protein expression in regenerating liver paralleled with those of control group. But the levels in low-dose-treated-group were greatly lower than that in high-dose-treated-group at each time point throughout the whole experiment. The actions of spermine were more obvious and longer. Conclusion Exogenous polyamines can induce antizyme express dose-dependently in early regenerating of rat liver, and the effects of spermine were more powerful than that of spermidine.