We report the cases of 22 patients who were hospitalized for pine oil cleaner ingestion. The toxic manifestations most commonly observed were mucous membrane and gastrointestinal irritation. Ataxia, which did not occur in adults, was a frequent presenting sign of intoxication in children. Fifty-nine percent of patients who ingested only pine oil cleaner developed central nervous system depression, and three of these developed coma. Three of five children and three of 17 adults developed acute hydrocarbon pneumonitis. Unlike aspiration pneumonitis, which follows petroleum distillate ingestion, chemical pneumonitis from pine oil cleaner may occur from gastrointestinal absorption of pine oil and deposition in lung tissue. However, recovery from pneumonitis in our patients was typically rapid and complete. Only two adults developed secondary bacterial pneumonia; no patient died. Ingestion of pine oil cleaner was rarely life threatening; most patients needed only gastrointestinal decontamination and minimal supportive care.