Objective: Anaemia is a significant complication of human immunodeficiency infection, causing life-threatening symptoms and impairing quality of life. This study aimed to assess the prevalence, severity and associations of anaemia, with cluster of differentiation 4 (CD4+) cell count and use of highly active antiretroviral therapy (HAART), in human immunodeficiency virus-infected patients. Material and Methods: Haemoglobin concentration, CD4+ count, HAART use and other factors were assessed in 372, adult HIV-infected out-patients; enrolled at a tertiary hospital in South-Eastern Nigeria. Anaemia was defined according to World Health Organisation criteria. Independent predictors were determined using bivariate analysis and enter method logistic regression analysis, at a p-value<0.05.Results: Prevalence of anaemia was 76.3% overall; 79.9% in females and 67.6% in males. Median CD4+ cell count was 609.50 (interquartile range 379) cells per microlitre (cells/μl). Females were more likely to be anaemic than males [odds ratio (OR)=1.88, 95% confidence interval (CI) 1.07, 3.31; p-value=0.011]. Furthermore, the odds of being anaemic were higher in participants 50 years or older (OR 3.79, 95% CI 1.36, 10.55; p-value=0.023). A CD4+ count <200 cells/μl. Not being on cotrimoxazole preventive therapy and a low monthly household income were associated with higher odds of anaemia. Tenofovir- and abacavir-based regimens were associated with lower odds of anaemia compared to zidovudine. Conclusion: Gender and the age of patients were independent predictors of anaemia. Pre-treatment screening, and close follow-up monitoring for anaemia as well as increased access to less haematotoxic HAART regimens are needed.