BACKGROUND: Chemotherapy-induced neutropenia (CIN) can result in poor tolerance of chemotherapy, leading to dose reductions, delays in therapy schedules, morbidity and mortality. Actively identifying predisposing risk factors before treatment is of paramount importance. We hypothesised that chemotherapy is associated with a greater increase in CIN and its complications in HIV-infected patients than in those who are not infected. OBJECTIVE: To establish the incidence of CIN in HIV-infected and uninfected patients undergoing chemotherapy. METHODS: A retrospective chart review and analysis was conducted in the oncology departments at Inkosi Albert Luthuli Central Hospital and Addington Hospital, Durban, South Africa. The study population consisted of 65 previously untreated women of all ages with stage II - IV breast cancer and known HIV status treated with neoadjuvant chemotherapy from January 2012 to December 2015. RESULTS: HIV-infected patients formed 32.3% of the group, and 95.2% of them were on antiretroviral therapy. The mean age (standard deviation (SD)) of the cohort was 48.5 (13.2) years (40.6 (9.6) years for the HIV-infected group v. 52.0 (13.1) years for the uninfected group; p<0.001). Ninety-five neutropenia episodes were observed (rate 0.85 per 1 year of follow-up time). Following multivariate adjustment, patients with HIV infection were almost two times more likely to develop CIN (hazard ratio (HR) 1.76, 95% confidence interval (CI) 1.06 - 2.92; p=0.029. A high baseline absolute neutrophil count (ANC) (HR 0.80, 95% CI 0.68 - 0.95; p=0.005) remained significantly associated with protection against CIN. CONCLUSIONS: HIV-infected patients were younger than those who were not infected, and presented at a more locally advanced stage of disease. HIV infection was an independent predictor for CIN. HIV-infected patients had an almost two-fold increased risk of developing CIN and developed neutropenia at a much faster rate. A high baseline white cell count and ANC were protective against CIN.