The peculiar i t ies of re ta ining BSP were invest igated in hepatic diseases, especially for the purpose to s tudy the pathogenesis of const i tu t ional hyperbi l i rubinemia. Methods and Subjects: Total (T), free (F) and conjugated (C) BSP levels were examined by chromatography before and 15 minutes a f te r in t ravenous inject ion of dehydrocholic acid (DHC) of l g , which were performed immediately a f te r collecting a blood sample at 45 minutes in routine BSP test . The subjects included 16 l iver cirrhosis, 18 hepat i t is , 22 obstruct ive jaundice and 4 const i tut ional hyperbi l i rubinemia, diagnosed by biopsy, operat ion or autopsy. Results: a) In l iver cirrhosis, F-BSP decreased, but C-BSP showed li t t le changes af ter DHC injection. b) In hepat i t is , T-BSP and F-BSP showed no uni form changes. Elevat ion of C-BSP was observed in th ree cases with pers is tent hepat i t i s . c) In ex t rahepat ic obstruct ive jaundice, depression of F-BSP and elevat ion of C-BSP were observed af te r the injection. In in t rahepat ic obstruct ive jaundice, the changes in T-BSP, F-BSP and C-BSP were not uniform, but C-BSP/F-BSP rat io was h igher t h a n tha t in extrahepat ic . d) In const i tu t ional hyperbi l i rubinemia, Dubin-Johnson's syndrome showed s t r ik ing elevat ion of T-BSP, F-BSP and C-BSP af ter the inject ion. The elevation was more marked than spontaneous elevation observed character is t ical ly in this disease af ter rout ine BSP test . On the contrary in Rotor 's hyperbi l i rubinemia, T-BSP and F-BSP showed dis t inct depression af ter the injection.