Objective:To observe the effect of irradiation and freezing on the survival of Clonorchis sinensis in their final host,fresh water fishes. Methods: Fresh water fishes contaminated with Clonorchis sinensis metacercarias were divided into two groups. One was irradiated with Cobalt 60 at the dose between 0 05 and 0 25 kGy, the other was frozen at -20c for 3 to 28 days.Fishes in both treated groups were ground, digested with pepsine and orally administered to rabbits.Fecal examination for ova and dissection of infected rabbits for adult worm were carried out to estimate the effect of both treatment methods on the survival of Clonorchis sinensis metacercarias. Results: No adult worm and eggs were found and no any pathological changes in liver and gallbladder were observed after 45 days. Conclusion: The results suggested that Clonorchis sinensis metacercarias irradiated at a dose of 0 15 kGy or frozen at -20c for 3 days lost their infectious capacity.