The present study was to investigate whether metallothionein (MT) was involved in sensitivity of testis to cadmium (Cd) and protection of rats from Cd-induced testis damages. The rats were treated by intraperitoneal injection with 0.2, 0.4, and 0.8mg Cd/kg BW for 7 days. The atomic absorption spectrophotometry and cadmium hemoglobin affinity assay were applied to evaluate the contents of Cd and MT in testis and liver. The testis glutathione (GSH), malondialdehyde (MDA) and daily sperm production were measured. There were substantial increases of both Cd and MT in the liver after Cd exposure. The testis Cd and MT contents were lower than those in the corresponding liver in Cd-exposed rats. Low doses of Cd (0.2 and 0.4mg/kg BW) induced MT in testis, while a significant decline of MT was found in rats treated with 0.8mg Cd/kg BW. By a concomitant decrease of MT, there was an obvious increase of MDA and marked decreases of GSH, daily sperm production in rats treated with 0.8mg Cd/kg BW. These findings suggested MT was more difficult to be induced in the testis than in the liver by Cd, which might account for the high susceptibility of testis to Cd. MT, increased by a low dose of Cd, played an important role in protecting testis against Cd toxicity by sequestering and antioxidating.