To investigate the cytogenetic abnormalitis in patients with diffuse large B-cell lymphoma(DLBCL) patients with bone marrow involvement and their influence on prognosis. Conventional karyotyping was performed on bone marrow specimens in 47 DLBCL patients with histologically confirmed bone marrow involvement(BMI). The karyotyping results of bone marrow, the characteristics and clinical effect of chromosomal abnormalities were analysed. In 47 DLBCL cases with BMI, the chromosomal abnormalities were detected in 25(53%) cases. Among them, complex karyotype was more frequent, being noted in 19(40%) patients. The most frequently involved chromosomes were chromosome 1 and 18(both 26%), others were chromosome 3(23%), 6(19%), 7, 8 and 14(13%). Among all karyotype changes, the most common numerical aberrations, in decreasing order of incidence, were trisomy 3(13%), trisomy 5, trisomy 7, trisomy 12, trisomy 18 and loss of 21(6%,each), and the most predominant structural aberrations, in decreasing order of incidence, wer