The study was designed to determine the associations of asymmetric (ADMA) and symmetric (SDMA) dimethylarginines plasma concentrations with all-cause mortality in patients with hematological malignancies. 33 patients with acute myeloid leukemia (AML), 31 patients with non-Hodgkin’s lymphoma (nHL), 32 patients with chronic lymphocytic leukemia (CLL) and 48 patients without malignancy were enrolled into the study. Each patient was followed until death or for at least 14.5 months (range: 14.5-53). Median ADMA and SDMA were significantly elevated in AML, nHL and CLL compared to controls (ADMA: 1.36, 1.24, 1.03, 0.55 mu mol/l respectively, p<0.0001; SDMA: 0.86, 0.76, 0.71, 0.52 mu mol/l respectively, p<0.0001). High ADMA and SDMA were associated with increased risk for all-cause mortality in CLL group (Hazard ratio (HR) for ADMA: 3.05, 95% CI:1.58-5.88, p = 0.001; HR for SDMA: 4.71, 95% CI:1.91-11.58, p = 0.001). Our study suggests that ADMA and SDMA could be novel prognostic factors for all-cause mortality in CLL patients.