A questionnaire survey was performed to investigate the actual hydration methods used with cisplatin-containing regimens at various institutions in Japan to gain an overview of the varieties employed. Replies were received from 368 of 686 institutions board-certified by the Japanese Respiratory Society. In 233 institutions (63%), new lung cancer patients were treated regularly with regimens containing cisplatin at ≥60 mg/m2. In 172 institutions (48%), hydration with <3000 ml of intravenous saline was performed on day 1. In 225 institutions (65%), hydration was performed for up to 3 days at most, but no more than 48 (14%) of the institutions that responded did so on day 1 only. Two to three weeks of hospitalization was needed for the initial course at most institutions (76%). Thirteen institutions (4%) treated patients as outpatients after the second course, whereas none did so from the beginning of treatment. Despite inconsistencies among the methods used by the various institutions, 84% of those surveyed considered their approaches to be appropriate. Some useful objective indices for deciding the volume or duration of hydration are needed.