Omega-conotoxin MVIIA ((J)-CTX) a neurotoxin isolated from the venom of Cone snail Conus magus, is a potent and selective blocker of the N-type voltage-sensitive calcium channel in neurons. Thereby it can inhibit the function of calcium chanel and neurotransmitter receptors, blocks the pain signal propagation to the brain or directly targets nociceptive neurotransmission. Ome-CTX has been cloned, expressed in the fusion form with thioredoxin (Trx-CTX ) in E. coli in the institute of biotechnology, Hanoi and finally purified. Trx-CTX could be produced in large amount, whereas the synthesis of omega-CRX is difficult due to the long synthetic process and low yield. In this paper, the authors presented study on analgesic activity and acute toxicity of Trx-CTX with the aim to test the possibility of the Trx-CTX for medical applications. The experiments were carried out in male mice of Swiss race weighing 20 g. The analgesic activity of Trx-CTX was measured in hot-plate assay. Its acute toxicity (LD50) was detenninated by the method described by Behrens and Karber. The results showed that Omega-conotoxin MVIIA in the fusion form with thioredoxin possess an analgesic activity 18 times better than morphin hydrochloride and its LD50 is detected at the dose of 775 ug Trx-CTX/g mouse body weight. Trx-CTX could be used for medicinal purpose.