Organophosphate poisoning occurs worldwide and often requires admission to an ICU. Grading of patients may be of value to identify high-risk cases but this has never been prospectively evaluated. Conventional treatment with atropine may lead to CNS toxicity, although control of secretions may still be inadequate. We conducted a randomized, controlled trial in 44 patients to compare atropine with glycopyrrolate, a drug that may provide better control of secretions and does not cross the blood-brain barrier. Grading was performed prospectively and compared to outcome. Thirty-nine cases were evaluated (atropine 22, glycopyrrolate 17); the treatment groups were comparable at baseline. No differences could be detected in outcome except for a trend to fewer respiratory infections in the glycopyrrolate group. Thus, treatment with atropine and glycopyrrolate was equally effective. A grading of serious was associated with ventilation, complications, and a prolonged ICU stay. A revised simplified grading is proposed.