The study was purposed to explore the relationship between the expression of deoxycytidine kinase (dCK) gene and fludarabine (Flud) resistance in patients with chronic lymphocytic leukemia (CLL). The real time quantitative polymerase chain reaction (RQ-PCR) technique was used to detect the mRNA expression of dCK gene in the bone marrow or peripheral blood mononuclear cells from 30 CLL patients, the difference of dCK expression levels between CLL patients sensitive to Flud and patients resistant to Flud was analyzed. The results showed that dCK expression level in the Flud-sensitive patients was much higher than that in the Flud-resistant ones (p = 0.001); dCK expression level had no relationship with sex, age, Binet stage, IgVH mutations, CD38, ZAP-70 or p53 gene mutation (p > 0.05). It is concluded that low expression or deficiency of dCK in patients may contribute to resistance against Flud- and the prognostic significance of dCK expression remains to be further studied.