The purpose of this study was to evaluate the ability of the test of variables of attention (TOVA) to distinguish between 6- to 12-year-old Japanese male children with attention deficit hyperactivity disorder (ADHD group; n=17) meeting DSM-IV and ICD-10 criteria, and age-matched, normal Japanese male controls (control group; n=19). The TOVA is a computer-administered, visual continuous performance test that provides measures of attention. The ADHD group had significantly higher means than the control group in all variables: omission errors, commission errors, response time, response time variability, anticipatory responses, and multiple response. Control children exhibited age-related changes in two variables: response time and response-time variability, but no age-related changes were observed in any variables in the ADHD group. This preliminary study indicates that the TOVA makes a useful contribution to the diagnosis of Japanese male children with ADHD.