Catheter-related thrombosis (CRT) is a serious complication in hematological patients, but the risk factors for its occurrence are not well established. The study objectives were to estimate the incidence of CRT and to identify the risk factors for developing CRT in hematological patients. In a prospective setting, 104 consecutive patients with 200 insertions of central venous catheters were enrolled into the study. The patients were screened for CRT by compression Doppler ultrasound every 10-14 days. Additionally, ultrasonography was performed in the case of clinical symptoms suggesting CRT. Over the course of 6,098 catheter days of follow-up, the incidence of CRT was 13.5 %. In 18/27 cases (66.6 %), radiological evidence of CRT was preceded by clinical symptoms. However, in 9/27 (33.3 %), CRT was clinically asymptomatic. The median times to symptomatic and asymptomatic CRT were 17 (range 1-49) and 8 (range 1-16) catheter days, respectively. In univariate analysis, the risk factors for CRT were exit-site infection (ESI) (P < 0.001), two or more prior chemotherapy lines (P = 0.015), catheter-related blood stream infection (P < 0.001), and Coagulase-negative staphylococci infection (P = 0.002). In multivariate analysis, ESI (OR 5.0; 95 % CI 1.6-6.3; P = 0.006) and two or more prior chemotherapy lines (OR 3.57; 95 % CI 1.27-10.11; P = 0.015) remained significantly associated with the risk of CRT. The results of our study provide information regarding the characteristic features of the patients who are at high risk of thrombosis, for whom Doppler ultrasound screening should be considered.