The patient was a 68-year-old woman who was diagnosed as having Ph-positive acute lymphoblastic leukemia (ALL). Complete remission (CR) was not obtained with the induction therapy of the Japan Adult Leukemia Study Group Protocol. We then considered administration of imatinib (ST1571). The institutional review board of our hospital approved this therapy, and we initiated the administration of imatinib 400 mg/day after obtaining written informed consent from the patient. At day 10 of the regimen, CR was achieved, treatment had to be discontinued RT-PCR showed no induction of detectable minor bcr-abl mRNA after three courses of consolidation chemotherapy combined with imatinib. We changed the administration protocol of Imatinib to two weeks out of every in four, weeks, and conducted 9 courses of consolidation chemotherapy. The negative result of RT-PCR has been maintained 10 months after diagnosis. The adverse effects were body weight gain and retaining pleural effusion, and these were controlled by the diuretics. The negative result of RT-PCR in Ph positive ALL after chemotherapy has rarely been reported, so the combination of imatinib and chemotherapy may be considered to be effective for Ph positive ALL.