To find an adequate pretreatment method of urine and serum, and to apply the methodfor the determination of 170S conjugates proposed previously to the field of clinical chemistry, we examined pretreatment of urine and serum samples. On the basis of results of the present study and the previously proposed methods, we developed the method for the determination of four 17OS sulfates and seven glucuronides in urine and four 170S sulfates in serum.