OBJECTIVE: To demonstrate primary tumour down staging benefit of neoadjuvant chemotherapy. BACKGROUND: In Nigeria, breast cancer has now replaced cervical cancer as the commonest female malignancy. Breast cancer in Nigerian women is characterized by young age at presentation, mostly premenopausal, and present at advanced stage of the disease with poor survival. Neoadjuvant chemotherapy [NAC] has become a valuable strategy in the multimodal treatment approach of locally advanced breast cancer [LABC], it results in tumour down staging benefits. PATIENTS AND METHODS: This is a prospective study of premenopausal LABC patients attending Nnamdi Azikiwe University Teaching Hospital Nnewi, from June 2009 to May 2010. Consenting patients received four courses of combined intravenous cyclophosphamide, doxorubicin and 5-fluorouracil (CAF) as neoadjuvant chemotherapy. Extent of response of primary tumour to NAC was determined using modified RECIST methodology. The relationship between clinical response and initial size of primary tumour and the toxicity profile was assessed. Significance of clinical response was determined using one sample T-test and correlation between variables using chi-square test. RESULTS: There were 31 evaluable cases with a mean age of 42.1 years [Range 26-51 years]. The mean diameters of breast lump, pre-chemotherapy and post-chemotherapy were 11.5cm [Range 5-25cm] and 7.5cm [Range 0-28cm] respectively. The pre-chemotherapy stage distributions were stage IIB=1(3.2%), IIIA=3(9.7%), IIIB=22(71%), IIIC=5(16.1%). The clinical response rate was 74.2% for breast tumour (complete clinical response cCR=12.9%, partial response PR=61.3%), 46.1% for axillary nodes (cCR, 34.6%; PR, 11.5%), and 20% for supraclavicular nodes (cCR, 20%). The clinical response of the breast tumour was statistically significant (p < .0001). Side effects of the NAC were generally mild and manageable within available resources. There was no statistically significant difference between primary tumour size, haematological side effects and alopecia when correlated with clinical response. CONCLUSION: This study has shown that neoadjuvant chemotherapy produces statistically significant clinical response in premenopausal LABC in our patient population which is not dependent on pre-chemotherapy primary tumour size. However, these findings need to be validated by further study recruiting a larger study population.