The Mania Rating Scale (MRS) was evaluated for use in prepubertal children. Eleven manic and 11 matched controls with attention-deficit hyperactivity disorder were examined. MRS scores were significantly higher in manic versus ADHD children (p less than 0.0001), while scores on hyperactivity rating scales (Conners-Parent and Teacher Forms) did not differ between groups. Most individual MRS item scores differed significantly between groups (p less than 0.05). MRS scores correlated significantly with severity of mania (Clinical Global Impression--Mania, r = 0.84; p less than 0.0001). Age, race, and sex were not correlated with MRS scores. The MRS may be useful in differentiating mania from ADHD and determining the severity of mania in prepubertal children.