The peritoneal absorptive function was observed on the rabbits with the intraperitoneal administration of BSP by the vicissitude of BSP concentration in peripheral blood. And the results were as follows. 1. The peritoneal absorptive function became the highest at 30 minutes-1 hour after the intraperitoneal administration without the relation of BSP concentration or BSP dosis injected into the peritoneal cavity. 2. The peritoneal absorptive function of pigment was increased in the dilution of BSP with physiogical salt solution on the intraperitonsal administration of BSP in the same dosis into the same individual. 3. The absorption curve showed a slack curve after 24 hours of injection and it was hard to get down to 0% after both of 24 hours and 48 hours. 4. The higher the maximum concentration get, the sharper was the absorption curve, except the cases with general narcosis of thiobal. In other words, it was almost same to that of the cases with the low value of maximum concentration, even in the cases with the highest value of maximum concentration and it showed around 5%, i.e. it was thought that the excretion into the bile duct was rapid with the concentration in blood. 5. The maximum concentration was high under the general narcosis by thiobal and showed 100% in some cases. It was thought that the high maximum concentration was caused by the acceleration of peritoneal absorptive function and the temporary decline of liver function. 6. The best method was the intraperitoneal injection of BSP 50 mg per kg in the dilution with 30 cc of physiological salt solution into rabbits through the region with local narcosis of procain hydrochloride.