About 5% of the patients admitted to emergency departments with poisonings are seriously ill and need admission to intensive care units (ICUs). This paper presents the result of three multicentric studies carried out in Spain during the last ten years. A study was made of 6 ICUs in 1980, 41 in 1987 and 15 in 1990 with a total of 596 patients. The average age (36) remained stable throughout, but the number of female cases decreased each time. The most frequent cause (79%) was attempted suicide. The products used most frequently were therapeutic drugs (82, 71 and 58%) followed by drugs of abuse, and then agricultural, household and industrial products. We observed a progressive decrease in barbiturates (54, 15 and 2%) and an increase in benzodiazepines and cyclic antidepressants. Therapeutic methods used were mostly gastric lavage (64%), activated charcoal (35%), forced diuresis (43%), extracorporeal therapy (11%) and antidotes. The mortality rate fluctuated between 6.4 and 9.1%, being significantly higher with poisoning by non-therapeutic drugs. In conclusion, the most common poisoning admitted to our ICUs was by psychoactive drugs in suicide attempts. We observed the under-use of activated charcoal and an excessive usage of kidney and extracorporeal methods. The prognosis was worse for poisonings with non-therapeutic drugs.