Visual contrast sensitivity (VCS) was measured in 30 alcoholic patients and 52 controls. The results showed a significant reduction in VCS for all the spatial frequencies. The mean reduction for all spatial frequencies was 2.49 dB below the level of the control group. Optimal sensitivity corresponded to a lower spatial frequency in patients than controls, i.e. 1 cycle/degree (c/d) versus 2 c/d. Curves for VCS were normal for five patients. Abnormalities in VCS were suggestive of optic nerve dysfunction for 15 patients (50%), which were probable in seven cases (23%) and possible in eight others (27%). For 10 subjects, the abnormalities were indicative of ametropia. Daily alcohol intake and daily tobacco consumption were not significantly different in the patients who displayed VCS abnormalities, reflecting alcohol-tobacco amblyopia, from those who did not. The presence of higher gamma-glutamyl transpeptidase and mean corpuscular volume levels in patients who had VCS abnormalities indicative of alcohol-tobacco amblyopia suggests that alcohol consumption is involved in the development of these abnormalities.