Background . The causes of anaemia have regional variations, and further variation is expected among paediatric hospital patients. However, the prevalence of anaemia and its contributing risk factors among paediatric patients remain understudied in South-East Nigeria. Methods . The study involved 286 anaemic (haemoglobin (Hb) ≤10 g/dL) and 295 non-anaemic preschool children attending a hospital outpatient department. A clinical research form was used to document demographic data, anthropometric measurements, disease details and packed cell volume. Common anaemia risk factors previously documented were studied. The prevalence rates of the independent variables were calculated and level of significance was determined, using χ². Results . The prevalence of anaemia was 49.2%, with the highest prevalence among children <12 months old (p=0.009). There was a significant association between anaemia and maternal education above primary education (p=0.01), but there was no association with socioeconomic status (p=0.7) or nutritional status (p=0.1). The prevalence of the major risk factors among anaemic children was: malaria parasitaemia 48.3% (p=0.03), iron deficiency 42.3% (p=0.001), glucose-6 phosphate dehydrogenase (G6PD) deficiency 24.8% (p=0.02), HIV seropositivity 13.3% (p=0.02), sickle cell anaemia 2.4% (p=0.3) and helminth infection 1.1% (p=0.32). Conclusions . Malaria and iron deficiency remain common among ill children <5 years old who are anaemic. The treatment of these conditions should be considered when managing an anaemic ill child in order to reduce morbidity and mortality.