The effect of Piracetam on attention deficit and hyperactivity disorder (ADHD) was studied on 25 children with developmental delay in placebo-controlled cross over study. Placebo or piracetam as suspension was administered to the children 50 mg/kg/day in 3 divided doses for a period of 3 weeks. After a wash out period of 2 weeks the treatment was resumed reversely. ADHD was induced and increased in the group taking piracetam significantly more than in the placebo group (P<0.05). Thus, piracetam in children with developmental delay induces and increases ADHD and should be taken cautiously.