A retrospective analysis was made concerning 1340 admissions to a multidisciplinary Intensive Care Unit over four years (1986-1989), because of acute poisoning. In 666 patients occurred 735 drug overdoses and in 674 patients, 691 non-drug intoxications. The drugs with main action in central nervous system were the most frequent in drug overdoses and the organophosphates insecticides in the non-drug intoxications. During the considered period there was an absolute and relative fall in the number of admissions for acute poisoning (480 vs 244, 15.1% vs 9.9%). The patients admitted were 698 men (289 in drug-overdoses and 409 in non-drug group) with a statistically significant difference between the type of intoxication and sex (p less than 0.001). Age mean was 40.2 +/- 19.6 years, almost the same in the two groups of intoxications. The peak incidence occurred from March to October. From the hospital area of Lisbon came 814 patients and outside of Lisbon 495 patients. The mean duration of stay in the ICU was 3.90 +2- 6.15 days, being 2.71 +/- 3.80 in the drug overdoses and 5.08 +/- 7.62 in non-drug intoxications (p less than 0.001). From the therapeutic measures we emphasize mechanical ventilation (29.5%), total parenteral nutrition (18.5%), dialysis (2.9%), Swan-Ganz catheter (2.8%) and pacemaker (1.2%). The mortality rate was 13.7%, higher in non-drug intoxications (23.0%) than in drug overdoses (4.4%) (p less than 0.0001).