Objective: The aim of the present case-control study was to determine whether or not the prevalence of gallbladder stones (GBS) was increased in patients with chronic myelocytic leukemia (CML) and to investigate clinical and laboratory characteristics of CML patients with GBS. Subjects and Methods: This study included 56 patients with CML and 55 sex- and age-matched healthy controls. All participants underwent abdominal ultrasonography and the main clinical and laboratory characteristics were recorded. Results: Gallbladder stones were detected in 13 (23.6%) patients with CML and in 3 (5.4%) control individuals (p < 0.05). The mean follow-up period of CML patients after diagnosis was 54.6 months, range 3–120 months. Hemoglobin levels were higher in the control group than in CML patients. However, total bilirubin, unconjugated bilirubin, lactate dehydrogenase levels, leukocyte and thrombocyte counts, frequency of splenomegaly and hepatomegaly were higher in the CML than in the control group (p < 0.05). Other clinical and laboratory values were not significantly different between the groups. CML patients with and without GBS were also compared for clinical and laboratory values. Age and follow-up period of CML patients after diagnosis were higher in the CML patients with GBS (p < 0.05). Conclusions: Higher prevalence of GBS in CML patients than in healthy controls was detected. We suggest that CML may increase the frequency of GBS, apart from other well-known risk factors. This risk is probably related to increased unconjugated bilirubin, which determines hemolysis, older age and long follow-up period of CML patients after diagnosis.