Human circulating lymphocytes were isolated and incubated with ethanol. Cytosolic, membrane-bound and total detergent extractable protein kinase C (PKC) activities were measured. Exposure to ethanol (100 mm) resulted in an increase in PKC activity, with membrane-associated PKC activity increasing with respect to cytosolic activity at 5 min of exposure. Higher concentrations of ethanol up to 200 mm were associated with increases in total detergent extractable PKC activity. Ethanol was the most potent of a series of straight chain alcohols studied for their effects on detergent-extractable PKC activity.