: To evaluate the knowledge of breast cancer diagnosis and treatment among female health professionals in a government health institutions in Sagamu, Ogun state, Nigeria. DESIGN: Descriptive study. SETTING: Olabisi Onabanjo University Teaching Hospital (OOUTH), Sagamu, Ogun State, Nigeria. SUBJECTS: One hundred and sixty two female health professionals. RESULTS: Study population comprised of doctors (9.3%), nurses (78.4%) and Pharmacists, radiographers and lab scientists (P/L/R) (12.3%) with mean age of 32.97 ± 0.92. The practice durations of the respondents ranged from 0 - 10 years (46.3%) and above 30 years (9.9%). The doctors and the P/L/R had 100% knowledge while the nurses had 96.9% as regards early diagnosis of breast cancer improving survival. The nurses had a higher knowledge (98%) in response to breast cancer can be treated surgically while the doctors had the least knowledge (86.6%), p value=0.021. Knowledge of these professional was also very satisfactory with years of practice as those of above 21years experience had higher knowledge when compared with lower years of experience. CONCLUSION: This study indicated that these female health professionals had a very satisfactory diagnostic and treatment knowledge which is higher than some earlier studies. This knowledge though commendable should be improved upon through consistent education of these professionals. KEYWORDS: Breast cancer, diagnosis and treatment, Health professionals, Teaching hospital.