Intracranial hemorrhage (ICH) is a rare but fatal central nervous system complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, factors that are predictive of early mortality in patients who develop ICH after undergoing allo-HSCT have not been systemically investigated. From January 2008 to June 2020, 70 allo-HSCT patients with ICH diagnosis formed the derivation cohort. Forty-one allo-HSCT patients with ICH diagnosis were collected from 12 other medical centers during the same period, and they comprised the external validation cohort. We used these 2 cohorts to develop and validate a grading scale that enables the prediction of 30-day mortality from ICH in all-HSCT patients. Four predictors, lactate dehydrogenase level, albumin level, white blood cell count and disease status, were retained in the multivariable logistic regression model, and a simplified grading scale, termed the LAWS score, was developed. The LAWS score was adequately calibrated (Hosmer-Lemeshow test, p>0.05) in both cohorts. It had good discrimination power in both the derivation cohort (C-statistic of 0.859, 95% CI 0.776-0.945) and the external validation cohort (C-statistic of 0.795, 95% CI 0.645-0.945). The LAWS score is the first scoring system capable of predicting the 30-day mortality from ICH in allo-HSCT patients. It showed good performance in identifying allo-HSCT patients at increased risk of early mortality after ICH diagnosis. We anticipate that it would help risk-stratify allo-HSCT patients with ICH and facilitate future studies on developing individualized and novel interventions for patients within different LAWS risk groups.