Since the middle of April 1955 there have occured in a certain dry-cleaning establishment in Okayama City cases believed to be trichloroethylene (C(2)HCl(3)) poisoning so that we measured the concentration of trichloroethylene in the air of the factory and at the same time examined the workers of the said factory from the standpoints of environments and psychiatry. The outline of results are as follows: 1. The trichloroethylene corcentration in the air highly exposed to the workers during working hours was found to be 420-990 ppm; and considering the generally-accepted maximum allowable concentration of 200 ppm, the air in the factory seems to have contained trichloroethylene in a sufficiently high concentration as to cause chronic poisoning in workers. 2. The trichloroacetic acid content in the urine of the majority of workers immediately after the work was 300-600 mg/l, obviously surpassing the maximum permissible content of 75 mg/l. 3. In one case thought to be showing relatively advanced symptoms, the trichloroacetic acid content in the urine and the same in the blood tended to be higher. 4. On the factual examinations in the factory where trichloroethylene is used, it seems the determination of the trichloroethylene concentration in the air and of the trichloroacetic acid in the urine and the blood of workers is an effective measure to be taken. In view of the fact that actually it is very difficult to evaluate the average concentration of trichloroethylene in the air during working hours, the determination of trichloroacetic acid in the urine of workers seems to be extremely significant. 5. As generalizing subjective and objective symptoms in the workers (5 persons) showing the poisoning symptoms, there are intoxication, disturbances in synergic movements, addiction, abstinent phenomena, insomnia, shoulder and back aches, tooth ache, disturbance in eye-sight, epiphora, changes in appetite and taste, decline in intelligence, bad humor, and intolerances for alcohol, for subjective symptoms; peculiar fat face, disturbance in minute synergic movement of fingers, atrophy of limb muscles, hypogeusia, ageusia, profuse sweating, decline in intelligence, slow-wave on E.E.G., and slight anemia may be pointed out as objective symptoms.