Of 2,360 victims of acute carbon monoxide intoxication examined between 1976 and 1981, delayed neurologic sequelae were diagnosed in 65 (2.75% of the total group, 11.8% of those admitted). There were 25 men and 40 women. Ages ranged from 34 to 80 years (mean, 56.1 years), with the peak incidence in the sixth and seventh decades. The lucid interval before appearance of neurologic sequelae varied from two to 40 days (mean, 22.4 days). The most frequent symptoms were mental deterioration, urinary or fecal incontinence, gait disturbance, and mutism; the most frequent signs were masked face, glabella sign, grasp reflex, increased muscle tone, short-step gait, and retropulsion. There were no important contributory factors except age and the severity of anoxia. Previous associated disease did not hasten the development of sequelae. Of 36 patients followed up for two years, 27 (75%) recovered within one year.