Aims. Carry-over effects or the hangover hypothesis postulates that alcohol continues to impair performance the morning after drinking, even after low or moderate doses. Performance deficits have been attributed to the residual effects of recent drinking. The present study examined evidence for residual alcohol consumption on human performance when blood alcohol level has declined to zero. Design. A within-subjects, repeated measures, placebo controlled experiment was conducted with double-blind alcohol administration to investigate the effects of alcohol the morning after ingestion. Setting. All subjects were studied in Glasgow, Scotland, UK. Participants. Forty healthy male moderate to heavy social drinkers between 18 and 45 years of age. Measurements. Psychomotor performance, subjective state and quality of sleep were examined under alcohol and placebo with a 1-week interval between test sessions. Enough alcohol was given to place subjects above the legal limit for driving at peak blood alcohol. Findings. There was no evidence for impaired performance the morning after ingestion. Effects were found for subjective state and sleep quality. Conclusions. The findings suggest that after a 100 mg/100 ml dose of alcohol people who: (a) have no alcohol left in their blood and; (b) do not feel hung over will generally be fit to drive.