Ten patients with acute myelogenous leukemia or high risk myelodysplastic syndrome who had achieved complete remission following treatment with the CAG regimen were monitored for peripheral blood WT1 expression mRNA levels. Induction therapy with the CAG regimen did not seem to be enough to lower WT1 expression levels to the normal range. In comparison with patients who received intensive chemotherapy for post-remission therapy, those who received only CAG therapy showed higher levels of WT1 expression and more easily relapsed. These data suggest that CAG therapy alone might not be sufficient to maintain complete remission and WT1 monitoring could be useful in the choice of appropriate post-remission therapy after achieving remission with the CAG regimen.