Organophosphate compounds (OP) are usual insecticides and may poison human beings in a suicide attempt or accidental exposure. They inhibit activity of cholinesterase. Poisoning may be enough sever for intensive care support. In this paper, we study the prevalence and management of sever cases as well.We studied patients with OP poisoning, from November 2002 to November 2005 in Sina Hospital, Tabriz, Iran, retrospectively and found patients who needed intensive care. During 4 years study, we documented 80 patients who were hospitalized due to OP poisoning and used drugs. Treatment with intravenous atropine and pralidoxime was started as soon as possible. We did not administer pralidoxim for 20 patients due to late admission (5 patients) and unavailability of the medicine (15 patients).Forty-five male and 35 female patients were enrolled in our study. The majority of the patients used OP for suicide attempt and 4 patients had accidental exposure. The mortality rate was 18% in patients who were treated with pralidoxim and patients without pralidoxim had a mortality rate of 21%. Ten patients were mechanically ventilated and the mortality rate was 50%. In patients without MV the mortality rate was 11.7%. The duration of intensive care stay was 7.1 +/- 2 days.Organophosphate compounds poisoning is a serious and lethal condition and needs early diagnosis and appropriate treatment. In patients with respiratory failure the mortality is very high; therefore we recommended early diagnosis, careful monitoring and appropriate management of complications in reducing the mortality rate.