We studied the relationship between alcohol consumption and arterial pressure in 1190 subjects of both sexes aged between 18 and 63 years who were examined during the course of a program of preventive medicine organized by Centro Diagnostico Italiano. In 711 subjects who were not requested to alter their usual alcohol consumption we found a significant relationship between alcohol consumption and systolic arterial pressure, b+SE(b), 4.6 --+ 2.1 mmHg/100 g ethanol/day. In particular, males who were heavy drinkers (>_ 50 g_ethanol/day) presented significantly higher systolic pressure levels than the other men, d_+_SE(d), 3.7 Β± 1.6 mmHg, whereas no significant differences were observed among the various classes of women subdivided according to alcohol intake (only 4.6% of the women consumed > 50 g ethanol/day). On the other hand, in 479 subjects who were requested to abstain from alcohol consumption during the three days preceding the examination, no significant relation was found between alcohol intake and arterial pressure. The difference between the systolic pressure levels of the male heavy drinkers and those of the male moderate and non-drinkers was only 0.1 mmHg. Excessive alcohol consumption, in this case, mainly in the form of wine, was therefore associated with higher systolic pressure levels. However, it seems that abstaining from alcohol for even a brief period may modify this relation considerably.