Chlorinated solvents are thought to be more nephrotoxic than nonchlorinated solvents in humans. Many workers have been exposed to trichloroethylene (TCE) because TCE is one of the most useful chlorinated solvents in some industries. Thus, to detect adverse effects of human exposure to TCE on kidneys, urinary total protein (U-TP) and beta-2-microglobulin (U-B2M) were determined in 104 male workers occupationally exposed to TCE and 102 male nonexposed controls. The workers have been probably exposed to 15 ppm TCE in air. The U-TP level of the workers, rather than the U-B2M level, was slightly higher than those of the controls. The differences of the U-TP level or the U-B2M level between the two groups, however, were not significant excluding an exception. (The mean U-TP level for 35- to 44-year-old workers was significantly higher than that for corresponding controls.) These results suggest that adverse effects of occupational exposure to TCE on kidney is very mild and glomerular rather than tubular.