Pipamperone solution or tablets were prescribed for four weeks to 188 patients (3-100 years) with behavior disorders. Fifty of these (group A) were mental retardates, the remaining 138 (group B) had a normal I.Q. Their doses were gradually increased until optimal effect was reached. Nearly all 17 items of a behaviour rating scale had improved very significantly by the end of the fourth week, while in 82% of the patients of group A and 76% of group B results were rated good to very good. Also, pipamperone proved to be far superior to previous psychotropic drugs in patients who had been treated before.