OBJECTIVE: Neurologic adverse events remain challenging complications with poor morbidity and mortality post adult allogeneic hematopoietic cell transplantation (allo-HCT) for hematologic diseases. We conducted a systematic review and meta-analysis to determine their spectrum, incidence, and impact on survival.METHODS: We searched MEDLINE, COCHRANE, EMBASE through March 2019 for all types of primary studies. Two independent reviewers screened, extracted data, and assessed risk of bias (RoB).RESULTS: We identified 552 eligible studies describing 57.972 patients; one randomized controlled trial, two case-control, 17 prospective, 86 retrospective cohort studies, 21 case series, and 425 case reports. RoB ranged from fair to high although case series were low-risk. The majority of studies traced infectious or drug-related neurologic manifestations. Infectious complications were present in 2.7% (95% CI 1.9-3.6) and 3.3% (95% CI 0.8-7.1) of patients in retrospective and prospective cohort studies, respectively. In retrospective studies, 3.4% (95% CI 2.1-4.9) of patients suffered from drug-related neurologic events. In prospective cohorts the equivalent incidence was 13% (95% CI 4.2-24.8). Neurologic complications had a detrimental impact on survival.INTERPRETATION: Our study highlights the wide spectrum and significant impact of neurologic complications on survival post allo-HCT. This systematic review summarizes existing data and provides the necessary background information for every physician involved in the management of these patients.