Objective: In critically ill patients, elevated blood lactate at admission is associated with poor outcome, but after aneurysmal subarachnoid hemorrhage, this has not been investigated. We studied the association between early circulating lactate and glucose with delayed cerebral ischemia and poor outcome. Lactate and glucose were both studied, hypothesizing that both may be increased due to sympathetic activation after subarachnoid hemorrhage similar to critically ill patients. Design: Retrospective cohort study. Setting: ICUs of two academic hospitals in the Netherlands. Patients: Patients with aneurysmal subarachnoid hemorrhage admitted to the ICU within 24 hours after the bleed surviving beyond 48 hours after ICU admission and who had at least one lactate measurement within 24 hours after admission. Interventions: None. Measurements and Main Results: In 285 patients, maximal lactate and glucose levels within the first 24 hours after admission were determined. Early lactate and glucose were related with delayed cerebral ischemia related infarction and poor outcome (a modified Rankin Scale score of 4, 5, or death at 3 mo). Delayed cerebral ischemia occurred in 84 patients (29%), and 106 patients (390%) had poor outcome. Multivariable analyses were performed with adjustment of established predictors for delayed cerebral ischemia and outcome: age, sex, World Federation of Neurological Surgeons grade at admission and Hijdra sum scores. Early lactate and glucose were strongly related (Spearman p = 0.55; p < 0.001). Lactate and glucose were both independently associated with delayed cerebral ischemia and poor outcome in multivariable analyses with either lactate or glucose as covariates. When both lactate and glucose were included, only glucose showed an independent association with delayed cerebral ischemia (odds ratio, 1.14; 95% CI, 1.01-1.28) and only lactate showed an independent association with poor outcome (odds ratio, 1.42; 95% CI, 1.11-1.81). Conclusions: Early lactate and glucose levels after aneurysmal subarachnoid hemorrhage are associated with delayed cerebral ischemia and poor outcome, suggesting that they may be considered in conjunction with other parameters for future prognostic models.