CNS complications of chronic alcoholism are frequently difficult to assess due to the variety of direct and secondary conditions which can result from alcoholic drinking and lifestyles. The influence of alcoholism and alcohol-related factors on the EEG of patients with chronic alcoholism was studied in 213 patients (15.4% of all adults who had EEGs) using visual analysis. The influence of a variety of alcohol-related factors - drinking history, clinical complications, traumatic head injuries, head CT findings and laboratory results - on the EEG and alcohol-related seizures was studied. The effect of EEG results on the decision to treat alcohol-related seizures was also assessed. 152 of the patients had seizures, mostly (90% of those with defined seizure types) generalized tonic-clonic seizures. 53% of all seizures occurred in the early withdrawal period (8 h to 7 days abstinence). A history of partial seizures was significantly associated with findings of focal EEG abnormalities, a history of head injuries and structural lesions on CT. The clinical significance of these findings was unclear, however, as the majority of patients who had focal EEG abnormalities or structural brain lesions still appeared to have generalized withdrawal seizures. The EEG and CT appeared to be complementary tests: for most patients, focal abnormalities were demonstrated on only one of the two tests. The majority of patients (56%) with normal EEGs had predominantly low voltage recordings (less than 25 muV), compared with 13.9% of 1167 patients without a history of alcoholism (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)