Background : Epidemiological studies of neurological complications in patients with hematological malignancies are scant. The objective of the study was to identify determinants of survival in patients with hematological malignancy and neurological failure. Methods : Post hoc analysis of a prospective study of adults with hematological malignancies admitted for any reason to one of 17 university or university-affiliated participating ICUs in France and Belgium (2010-2012). The primary outcome was vital status at hospital discharge. Results : Of the 1011 patients enrolled initially, 226 (22.4%) had neurological failure. Presenting manifestations were dominated by drowsiness or stupor (65%), coma (32%), weakness (26%), and seizures (19%). Neuroimaging, lumbar puncture, and electroencephalography were performed in 113 (50%), 73 (32%), and 63 (28%) patients, respectively. A neurosurgical biopsy was done in 1 patient. Hospital mortality was 50%. By multivariate analysis, factors independently associated with higher hospital mortality were poor performance status ( odds ratio [OR], 3.99; 95% CI, 1.82-9.39; P = 0.0009), non-Hodgkin's lymphoma ( OR, 2.60; 95% CI, 1.35-5.15; P = 0.005), shock ( OR, 1.95; 95% CI, 1.04-3.72; P = 0.04), and respiratory failure ( OR, 2.18; 95% CI, 1.140-4.25; P = 0.02); and factors independently associated with lower hospital mortality were GCS score on day 1 ( OR, 0.88/point; 95% CI, 0.81-0.95; P = 0.0009) and autologous stem cell transplantation ( OR, 0.25; 95% CI, 0.07-0.75; P = 0.02). Conclusions : In ICU patients with hematological malignancies, neurological failure is common and often fatal. Independent predictors of higher hospital mortality were type of underlying hematological malignancy, poor performance status, hemodynamic and respiratory failures, and severity of consciousness impairment. Knowledge of these risk factors might help to optimize management strategies.