We tested the hypothesis that phospholipids are altered in skeletal muscles of rats exposed to ethanol for either acute (2.5 hours) or prolonged (6 weeks) periods. In acute studies, rats were dosed with saline (0.15 mmol/l; controls) or ethanol (75 mmol/kg body weight; treated). There were four groups: (A) saline (control); (B) cyanamide (an aldehyde dehydrogenase inhibitor); (C) ethanol; and (D) cyanamide + ethanol. In prolonged studies, two groups of rats were fed liquid diets containing 35% of total dietary energy as either glucose [group (E)] or ethanol [group (F)]. At the end of the treatments, membrane phospholipids were measured in soleus (Type I fibre-predominant) and plantaris (Type II fibre-predominant) muscle. In acute studies, ethanol alone [(A) vs. (C)] and cyanamide + ethanol [(A) vs. (D)] significantly increased 18 : 2 in plantaris (p < 0.05), whereas in soleus none of the treatments had any effect on the phospholipids. In prolonged studies [(E) vs. (F)], there were decreases in 16 : 0 (p < 0.05) and 18 : 1 (p < 0.01) and increases in 18 : 2 (p < 0.001) in plantaris. In soleus, decreases in 18 : 1 (p < 0.05) and increases in 18 : 2 (p < 0.01) occurred. In conclusion, alterations in the proportions of 16 : 0, 18 : 1 and 18 : 2 provide evidence of an altered membrane domain which may contribute to the pathogenesis of alcohol-induced muscle disease. Changes due to prolonged exposure are more profound than those in acute exposure and the preferential effects in Type II plantaris may reflect the greater susceptibility of this muscle to alcohol.