OBJECTIVE: This study examines the cost of various platinum based chemotherapy regimes in the treatment of advanced non-small cell lung cancer (NSCLC) from the perspective of the Spanish health care system. METHODS: A retrospective economic analysis was conducted based on two published phase III randomised controlled trials of gemcitabine/cisplatin (GC) and other regimens. Comella et al (2000) compared GC with vinorelbine/cisplatin (VC); Schiller et al (2002) compared GC with paclitaxel/cisplatin (PC), carboplatin/paclitaxel (CP) and docetaxel/cisplatin (DC). As the efficacy of the compared regimens may be considered equivalent, a cost-minimisation analysis was conducted. Only direct costs were included in the analysis. Costs were compared across four main resource categories: chemotherapy acquisition, drug administration, hospitalisations and other medical resources. Spanish health care unit costs were drawn from the literature and public sources. RESULTS: The economic analysis applied to the Comella trial indicated that the total cost of the GC (€4097) regime was 84% of the VC (€4899) regime. When applied to the Schiller et al study, the total cost of the GC (€5154) regime was only 79% of the total cost for the DC (€6512) regime, 76% of the total cost of the PC (€6746) regime and 53% of the total cost of the CP (€9750) regime. CONCLUSIONS: For treatment of advanced NSCLC in Spain, GC show cost savings potential compared to with VC, PC, CP, and DC. The cost of acquiring chemotherapy is not the only direct cost that should be considered when treating patients with chemotherapy, drug administration, hospitalisations and other medical resources are costs that should be considered.