To investigate the problem of poisoning in Khonkaen Province, Thailand, a prospective data collection method was used. From 257 acute poisoning cases, the total poisoning rate was found to be 0.76/1000 hospital visits and the case fatality rate was 2.7%. Major types of poisoning found were poisonous animals (28.8%), agricultural chemicals (27.2%), misused therapeutic drugs (19.0%) and household chemicals (10.1%). Major causes of poisoning were suicide attempts (35.4%), accidents (28.4%), ignorance (26.8%) and occupational (8.6%). The most frequent age group affected was 11-30 y (58.8%). Females were found involved more than males (1.2:1). In males, the most frequent cause was unintentional poisoning; in females, it was from suicide attempts. The most frequent types among males were poisonous animals and agricultural chemicals; in females they were agricultural chemicals, misused therapeutic drugs and poisonous animals. The poisoning rate in children 0-5 was 12.1% of the total cases, and poisoning from every type of toxic substance was found. The cause in children was unintentional poisoning. The peak total poisoning time was from August to October.