This study examined the acid-base disturbances in 67 adults with salicylate intoxication. On admission, 66 patients had an acid-base distrubance. In contract to previous suggestions, however, only 25% of the patients had simple respiratory alkalosis. Unlike salicylate intoxication in children, 33% of these adults with salicylate intoxication had ingested additional drugs. These additional drugs generally were CNS depressants and were important determinants of the variety of the acid-base disturbance. Those patients who ingested additional drugs had a significantly lower incidence of respiratory alkalosis (P less than .005) and a higher incidence of respiratory acidosis (P less than .005) and acidemia (P less than 0.25). The incidence of acidemia correlated with the presence of neurological symptoms.