Pharmacokinetic studies on praziquantel in rabbits were performed in this paper. The pharmacologically active parent drug was separated from the pharmacologically inactive metabolites by HPLC method. The pharmacokinetic parameters of parent drug were obtained. In vitro partition to blood cells of praziquantel was measured. The mean value (n = 3) of partition to blood cells was 44% at concentrations between $1;{mu}g/ml$ and $40;{mu}g/ml$. Therefore, the relatively high partition to blood cells should be considered in further pharmacokinetic studies on praziquantel.