Thirteen guinea pigs and 23 rabbits were challenged with 300 metacercariae of Clonorchis sinensis each and the recovery of adult worms and egg counts in feces were compared at 11-13 weeks post-infection in guinea pigs and at 7-9 weeks post-infection in rabbits. The recovery rate of adult worm was 23.5 percent in guinea pigs and 20.l-30.5 percent in rabbits. The mean E.P.G. of these animals in above period of infection was 106 in guinea pigs and 121 in rabbits. When one hundredth of E.P.G. was expressed as X and the number of adult worms as Y, the relationships between X and Y were as follows; Y=0.8X+10.8 in guinea pigs and Y=0.7X+6 in rabbits.
