Abstract: 【Abstract】objective Firstly to investigate the significance of fluorescence in situ hybridization(FISH) in detecting cytogenetic aberrations in Chinese patients with chronic lymphocytic leukemia(CLL) and secondly explore the characteristics and prognostic significance of cytogenetic aberrations in Chinese patients with CLL．Methods Eighty-four cases of CLL detected by FISH with a panel of probes(CSP12(12p11.1～12q11.1), D13s25(13q14.3),ATM(11q22.3),RB1(13q14), p53(17p13.1)) were retrospectively analyzed by clinical manifestations, laboratory tests and prognosis. Results Cytogenetic aberrations were found in 62 of the 84 CLL patients(73.8%)．The most frequent abnormality detected was del(13q14) (56%), followed by del(17p13)(28.6%), del12(16.7%), del(11q22.3)(13.1%), trisomy 12(13.1%). The aberration of 12 deletion was a novel discovery. The trisomy 12 propotion of the group older than 60 was significantly higher than that of the group aged<60(24%VS3%, P=0.042)．There was no significant relationship between cytogenetic aberrations and sex, Binet stages, level of lactate dehydrogenase, expression of CD38. The proportion of CD38 expression in LDH elevation group was significantly higher than LDH normal group. (67%VS20%, P=0.015). The median survival time with del(17p13), or del(11q22.3) or complex cytogenetic aberrations was 75 months, the median survival time with sole del(13q14) was 150 months, the median survival time with the others was 120 months, but there was no significant deference with each other. Conclusions FISH is a rapid，accurate and sensitive technique for detection of cytogenetic aberration in CLL. The frequencies of the chromosomal abnormalities in Chinese CLL patients are similar to those in Western countries, but the aberration of 12 deletion was a novel discovery．

Key words: Leukemia，lymphocytic，chronic, Fluorescence in situ hybridization