Objective:To assess the prevalence,clinical characteristics and prognostic accuracy of non-thyroidal illness syndrome(NTIS)in patients with chronic lymphocytic leukemia (CLL). Methods:Thyroid function and clinical data were examined in 78 patients with CLL to identify potential predisposing factors,evaluate clinical features and overall survival(OS). Results:Among 78 CLL patients,14 patients were diagnosed as NTIS. NTIS of CLL was significantly correlated with advanced Binet stage (Binet C)(P=0.021),decreased hemoglobin(P < 0.001),platelet count(P=0.012)and albumin(P=0.018),and increased C reaction protein(CRP)(P=0.007). The patients with NTIS had shorter median OS than patients without NTIS (P < 0.001). Conclusion:NTIS was present in some CLL patients,and that may be related with systemic inflammation and nutritional decline of patients. CLL patients with NTIS have a poor prognosis.