Purpose Breast cancer is a major global health, gender and socioeconomic challenge. In PNG it is the leading cause of female mortality. Understanding direct medical costs related to breast cancer management can direct resource allocation and investment in breast cancer screening, treatment, infastructure and training. Methodology A cost of illness study was conducted amongst patients with breast cancer at Alotau Provincial Hospital from the 12th of January 2017– 9th of August 2022. A bottom up approach of micro costing was applied to estimate the patient and hospital perspectives of direct medical costs. Results The total cost of breast cancer management was K1,624,656.14 (US$471,150.28). 58.5 % (n = 38) of patients with breast cancer did not undergo any form of surgery. Hospital costs accounted for 99.7 % (K1,620,156.14, US$469,845.28) of the total direct medical costs. The average cost per patient was K24,994.71 (US$ 7248.47). The dollar conversion was 1 KINA = 0.29 USD. Conclusion Investment in screening, diagnosis and treatment is crucial in addressing the burden of breast cancer in PNG.