Eight workers occupationally exposed to acetone and eight nonexposed controls were investigated on nine shift days both during work and leisure. The mean exposure to acetone was near 1000 ppm (2400 mg/m3). Acetone in urine was moderately correlated to acetone in the air. Ratings on scales of well-being and acute symptoms (SPES) correlated significantly with concentrations of acetone in urine but not with concentrations of acetone in the air.