Recovery from anesthesia was assessed in a controlled manner in 34 healthy student volunteers, using a psychomotor test battery 1 and 5 hours and a driving simulator 2, 4.5, and 7 hours after 3.5 minutes of anesthesia with halothane or enflurane combined with nitrous oxide and oxygen. Psychomotor performances remained significantly (P < 0.05 to P < 0.001) worse than in an unanesthetized control group for 5 hours after both halothane and enflurane. However, impairment of driving skills 4.5 hours after anesthesia was measurable only after halothane (P < 0.05). It is concluded that after even brief periods of halothane or enflurane anesthesia patients should not drive or operate machinery for at least 7 hours. The magnitudes and durations of the residual effects of both agents on psychomotor performance were, however, less than those previously found after thiopental, methohexital, or diazepam.