To determine the chromosomal abnormalities and their clinical significance in adult acute lymphoblastic leukemia, karyotypic analyses with R- and/or G-banding were performed in 101 newly diagnosed ALL patients. The results showed that 69 (68.32%) cases had clonal chromosomal abnormalities and specific abnormalities including Philadelphia chromosome (32.67%), t(4;11) (2.97%), t(11;14) (3.96%), abnormalities of 8q24 (2.97%), 6q- (4.96%). Patients with Ph chromosome showed higher leukocyte counts and more frequent hepatosplenomegaly and most of them were L2 and B lineage subtypes. They had lower complete remission (CR) rate, needed longer time to achieve CR and relapsed earlier as compared with patients without Ph chromosome. These suggested that chromosomal abnormalities are very frequent and some specific abnormalities had specific clinical features.