: Background: Evidence suggests that alcoholics exhibit particular deficits in brain systems involving the prefrontal cortex, but few studies have directly compared patients with and without Korsakoff's syndrome on measures of prefrontal integrity. Methods: Neuropsychological tasks sensitive to dysfunction of frontal brain systems were administered, along with standard tests of memory, intelligence, and visuospatial abilities, to 50 healthy, abstinent, nonamnesic alcoholics, 6 patients with alcohol‐induced persisting amnestic disorder (Korsakoff's syndrome), 6 brain‐damaged controls with right hemisphere lesions, and 82 healthy nonalcoholic controls. Results: Korsakoff patients were impaired on tests of memory, fluency, cognitive flexibility, and perseveration. Non‐Korsakoff alcoholics showed some frontal system deficits as well, but these were mild. Cognitive deficits in non‐Korsakoff alcoholics were related to age, duration of abstinence (less than 5 years), duration of abuse (more than 20 years), and amount of alcohol intake. Conclusions: Abnormalities of frontal system functioning are most apparent in alcoholics with Korsakoff's syndrome. In non‐Korsakoff alcoholics, factors contributing to cognitive performance are age, duration of abstinence, duration of alcoholism, and amount of alcohol consumed.