Objective : Treatments for patients with mental retardation and pervasive developmental disorders are not curative, and are designed to help those with disabilities adjust to their environments and daily demands. As clinicians, the present authors tried to find agents with potentially curative properties. Among the numerous herbal formulations available, we chose and assessed Gami-jiwhang-tang (GJT) in the hope that it would improve cognitive development of children. Methods : Subjects were typically-developing healthy, 7- to 8-year-old boys and girls living in Seoul, Korea. The experimental group took GJT for six weeks and was followed up six weeks after discontinuation of GJT. The control group was assessed at the same intervals but did not receive placebos. To measure the effects of GJT, neuropsychological tests and intelligence test were taken before commencing GJT and twelve weeks later. Resulets and Conclusion : For all of the ANOVAs, the treatment by time interaction terms was not significant. However, the experimental group showed the tendency to be progressed in most subscales compared with the control group, especially on performance intelligence, visual organization, and verbal fluency. Conclusion : Although GJT failed to reveal significant improvement in cognition, we remain hopeful about the compound and believe that it should be evaluated by a double-blind, placebo-controlled trial in the future.