The study compared the efficacy, side effects, and safety of magnesium pemoline (Cylert) and destroamphetamine (Dexedrine) as compared with placebo. Subjects were 81 children, ages 6-12 years, who evidenced one or more signs of minimal brain dysfunction, and were referred with major complaints of hyperactivity, short attention span, distractibility, poor frustration tolerance, disruptive behavior, and academic problems. Subjects were randomly assigned to the three treatment conditions. During the 8 weeks, medical evaluation occurred four times, psychological testing twice, and parent and teacher ratings weekly. It was found that both drugs significantly reduced symptomatology over placebo controls. Dexedrine produced a more immediate and dramatic effect, with more patients being much improved. Cylert, however, did benefit a substantial number of patients, with fewer anorexic side effects. Neither drug produced hematologic, liver, kidney, or cardiovascular effects of consequence. (KW)