Symptoms and pulmonary function were evaluated in subjects exposed to trichlorophenol. Symptoms from upper airways and chest were more common among those exposed than in control subjects (60% and 10%, respectively) Significantly reduced forced expired flow at 75% of vital capacity [exposed: 5.721/s (5.08-6.85), mean and range; reference: 6.451/s (5.77-8.40), P less than 0.05] and increased closing volume [exposed: 25.2% (19.5-36.0), reference: 17.1% (12.0-23.5), P less than 0.01] were measured while other spirometric variables and the transfer factor of the lung for CO were normal. Increased elastic recoil pressure of the lung and signs of lung tissue engagement in X ray were noticed in two subjects. Blood and liver tests were normal. The findings suggest an irritating effect on the lung by trichlorophenol, and it cannot be excluded that long-term exposure may produce pulmonary fibrosis.