OBJECTIVES: In Brazil, 140 million citizens (~80% of the population) depend on the public health care system. Advanced gastric cancer (AGC) is the second most frequent cause of death in Brazil: 10,645 per year. This disease appears among the most costly cancers to treat. Objective was to identify the medical resource usage (MRU) to treat AGC and estimate the associated costs in the public health care sector in Brazil. METHODS: A questionnaire was developed to identify the medical resource usage (MRU) of managing AGC in the public healthcare system. The questionnaire was applied to 20 oncologists and 20 nurses in a structured interview. MRU data were extracted according to the following stages: 1) diagnosis and staging; 2) 1st line treatment, 3) 2nd line treatment; 4) best supportive care (BSC); and 5) terminal care. Then, modified Delphi panels were conducted in the 5 largest cities of Brazil to reach a consensus on the base-case value and on the possible ranges of each resource used. Financial values were translated into USD based on the exchange rate of R$2.40=US$1.0. RESULTS: The mostly used diagnostic procedures were upper digestive endoscopy, abdominal computed axial tomography (CAT) and thoracic radiography. For 1st line treatment, 5FU-based chemo was the first choice of 50% of the oncologists interviewed, either given in combination with cisplatin (22%), etoposide (17%) or cisplatin plus doxorubicin (11%). Most commonly used resources in BSC/terminal care were blood analysis and anti-algic radiation. The mean cost per patient were: diagnostic and staging: R$451 (US$188); 1st line treatment: R$4565 (US$1902); 2nd line treatment: R$2740 (US$1142); BSC: R$883 (US$368); and terminal care: R$416 (US$173). The total mean cost per patient were therefore R$9056 (US$3773) of which chemotherapy drugs represented 37%. CONCLUSIONS: Findings suggest that the total mean cost of treating AGC per patient in the public sector in Brazil is R$9056 (US$3773).