As a link in the studies on benzene poisoning, the butanone method for the microquantitative analysis of benzene in the air has been investigated, and also various conditions leading to the maximum development of the colour have been determined; and a situation of elimination of unchanged benzene, the ratio of ethereal sulfate to total sulfate and phenol in the urine after the rabbits receiving benzene have been studied. The results are as follows: 1. As for the concentration ethanol at 1-2 per cent, NaOH at 0.005-0.008 per cent and H(2)O at below 0.5 per cent proved to be optimal on the development of the colour by the butanone method. 2. After the administration of 200-500 mg benzene per Kg. body weight, benzene concentration in the exhaled air increased rapidly, and reached the maximum 2 hours after oral administration and intra peritoneal injection. Thereafter it decreased rapidly and became almost zero 15 hours later, while in the case of subctaneous injection, it reached its maximum 3 hours afterward, and thereafter, though gradually, the elimination continued over 24 hours after administration. 3. Ethereal sulfate ratio and phenol in the urine reached the maximum 24 hours after receiving benzene, but they returned to the normal level 48 hours afterward. 4. In the cases of 0.2-1.0 g/kg of benzene by various method, the ratio of eliminated benzene to administrated one obtained so far are as follows: as elimination unchanged 43.5-78% as ethereal sulfate 2.9-18% as phenol 3.2-16.7% as a whole, 73.5-83.9% has been eliminated.