To explore the cytogenetics and related clinical characteristics of adult acute leukemia with Philadelphia chromosome positive (Ph(+)AL), MIC classification by morphology, immunology and cytogenetics was used to retrospectively study 79 patients with Ph(+)AL hospitalized in the Institute of Hematology, People Hospital in Beijing from October 1991 to September 2003. The results showed that 6.9% cases were diagnosed as Ph(+)AL and classified into three subtypes: acute lymphoblastic leukemia (Ph(+)ALL) in 56 patients (18%), acute myeloid leukemia (Ph(+)AML) in 10 patients (1.2%) and mixed acute leukemia (Ph(+)MAL) in 13 patients. B-cell antigen expression was found in 52 out of 56 patients with Ph(+)ALL. 54.4% (43/79) patients had additional chromosome abnormalities including chromosome 7, double Ph and plus 8, etc. Complete remission (CR) rate of Ph(+)ALL and Ph(+)MAL was 57.0%, none of Ph(+)AML achieved CR. Median overall survival of Ph(+)ALL, Ph(+)MAL and Ph(+)AML were 10, 10 and 2.5 months respectively. It is concluded that Ph(+)AL has highly heterogeneity involving various differentiated stages of immature leukemic cells. Since the poor prognosis associated with this kind of AL, early diagnosis with MIC classification is a prerequisite to take more effective conditioning regimen and prospectively consideration of allogeneic stem cell transplantation to improve prognosis.