Background: Severe anaemia is a common childhood problem which is associated with various degrees of morbidity and mortality especially in children under five years of age. It remains a major public health challenge in Nigeria and sub-Saharan Africa. Objectives: To determine the prevalence, aetiology and outcome of severe anaemia in children aged 6 months to 5 years. Methods: This was a prospective study of children less than 5 years that presented with severe anaemia at the Children's Emergency Unit and the Outpatient Department of Ebonyi State University Teaching Hospital Abakaliki (EBSUTH), Abakaliki. Severe anaemia was defined as PCV ≤ 15%. Biodata of subjects selected included age, sex, and socioeconomic status. Laboratory tests carried out included haemoglobin levels, haemoglobin electrophoresis, blood film examination, blood culture, urinalysis, microscopy, and other relevant tests. Results: One hundred and forty subjects out of the 1450 patients admitted during the period of study had severe anaemia giving a prevalence rate of 9.7%. Majority of the patients (63.6%) were less than 2years of age. Malaria was the commonest cause of severe anaemia 64.3% (90). Other common causes included sickle cell anaemia 13 (9.3%), Septicemia 19 (13.6 %), and malnutrition 10 (7.1%). One hundred and seventeen (83.6%) patients recovered and were discharged home while 19 died giving mortality rate was 13.6%. Conclusion: The study revealed high prevalence of severe anaemia while malaria was observed to be the commonest cause among under-5 children seen at EBSUTH Abakaliki.