This study was to explore the stimulating effect of CpG-oligodeoxynucleotides (CpG-ODN) in combination with interleukin-2 (IL-2) on cytogenetic features of chronic lymphocytic leukemia (CLL) cells. Peripheral blood or bone marrow cells of 115 patients with CLL were cultured for 72 hours with CpG-ODN plus interleukin-2 (IL-2), and routine karyotype analysis was performed with R-banding technique. The metaphase number≥20 was considered as successful stimulation. The results showed that among the 115 CLL patients, successful stimulation rate was 74.8%. The rate of chromosome aberrations was 58.1%. One kind of aberration was detected in 21 cases (24.4%), two kinds of aberration in 6 cases (7.0%), complex aberrant karyotype in 23 cases (26.7%), included highly complex aberrant karyotype in 9 cases (10.5%), respectively. A total of 163 abnormalities of 102 kinds were detected in 86 patients. Number aberrations were 116 (71.2%), and structural abnormalities were 47 (28.8%). The most frequent number aberration was trisomy 12 (14.0%), and structural aberration was 15q+ (5.8%). It is concluded that most of CLL patients have chromosome abnormality, and the number abnormality are more frequent than the structural aberrations. CpG-ODN plus IL-2 can effectively raise the number of cells at metaphase and the detection rate of chromosome aberrations in CLL patients.