OBJECTIVE To study the clinical characteristics and therapeutic outcome of Ph+ acute lymphoblastic leukemia (ALL). METHODS Thirty previously untreated cases of Ph+ B-ALL were diagnosed in our institute. The patients were treated with combination chemotherapy of CODP +/- L regimen, Imatinib (400 approximately 600 mg/d) was continuously given to those who couldn't reach CR. Fourteen patients received allogeneic hematopoietic stem cell transplantation (allo-HSCT) after CR, while 16 received consolidation of intensive chemotherapy. RESULTS Thirty (32.6%) of 92 ALL patients were diagnosed as Ph+ ALL, with a median age of 25.5 (14 - 60). Among them Ph+ as the sole anomaly was seen in 16 patients, and Ph+ with additional chromosome abnormalities in 14. Besides the B cell markers, 23 (76.7%) patients had CD34+ and 13 (43.3%) CD13+ and/or CD33+. Nineteen of the Ph+ ALL patients underwent molecular analysis; 13 (68.4%) expressed P190 and 6 (31.6%) P210. Increased WBC (> 30 x 10(9)/L) was found in 22/30 cases while WBC > 100 x 10(9)/L in 9/30 cases. The chemotherapy complete remission rate was 68.8% in patients with only Ph+ versus 28.6% in those with additional chromosome abnormalities. All seven refractory/relapsed patients reached CR with Imatinib therapy. The total complete remission rate was 73.3% in all Ph+ ALL patients. The median remission duration was shorter in patients with additional chromosome than in those with only Ph+ (1 vs 7 months, P < 0.05), and so was the survival period (7 vs 9 months, P > 0.05). The remission duration was significantly longer in patients received allo-HSCT than in those received chemotherapy only (8 vs 0.5 month, P < 0.05), and so was the survival period (12.5 vs 6 months, P < 0.05). CONCLUSIONS Additional chromosome abnormalities negatively affect the prognosis and therapeutic effect of Ph+ ALL patients. Imatinib is effective for the induction therapy of Ph+ ALL. The survival period of patients who received allo-HSCT was obviously longer than those who received chemotherapy only.