The presence of melatonin in wine and different liquors was investigated and the intake of wine by human volunteers and possible increase of their serum melatonin levels was examined. Red and white wines, in addition to different liquors, were used to measure their melatonin content. Additionally, twenty volunteers aged from 25 to 49 drank 100 mL red or white wine, and serum melatonin levels were measured before and 1 h after wine intake. Melatonin was mostly present in red wine and lower levels were found in white wine and other liquors. Consequently, when human volunteers drank wine, the level of melatonin in serum was significantly higher 1 h after red wine intake than before. Thus, the presence of melatonin in relatively high concentrations in red wine and its contribution to increasing serum melatonin levels after its intake by human volunteers is demonstrated.