Background Lower haemoglobin levels may impair cerebral oxygen delivery and threaten tissue viability in the setting of acute brain injury. Few studies have examined the association between haemoglobin levels and outcomes after spontaneous intracerebral haemorrhage. Aims We evaluated whether anaemia on admission was associated with greater intracerebral haemorrhage severity and worse outcome. Methods Consecutive patients with spontaneous intracerebral haemorrhage were analyzed from the Registry of the Canadian Stroke Network. Admission haemoglobin was related to stroke severity (using the Canadian Neurological Scale), modified Rankin score at discharge, and one-year mortality. Adjustment was made for potential confounders including age, gender, medical history, warfarin use, glucose, creatinine, blood pressure, and intraventricular haemorrhage. Results Two thousand four hundred six patients with intracerebral haemorrhage were studied of whom 23% had anaemia (haemoglobin <120 g/l) on admission, including 4% with haemoglobin <100 g/l. Patients with anaemia were more likely to have severe neurological deficits at presentation [haemoglobin ≤100 g/l, adjusted odds ratio 4·04 (95% confidence interval 2·39, 6·84); haemoglobin 101–120 g/l, adjusted odds ratio 1·93 (95% confidence interval 1·43, 2·59), both P < 0·0001]. In nonanticoagulated patients, severe anaemia was also associated with poor outcome (modified Rankin score 4–6) at discharge [haemoglobin ≤100 g/l, adjusted odds ratio 2·42 (95% confidence interval 1·07–5·47), P= 0·034] and increased mortality at one-year [haemoglobin ≤100 g/l, adjusted hazard ratio 1·73 (95% confidence interval 1·22–2·45), P = 0·002]. Conclusions Anaemia on admission is associated with greater intracerebral haemorrhage severity and worse outcomes. The utility of transfusion remains unclear in this setting.