Background: Intraperitoneal (IP) chemotherapy with taxanes provides sustained high local concentrations, and the efficacy of IP paclitaxel (PTX) has been shown in ovarian cancer. We previously reported the safety and efficacy of IP PTX plus systemic chemotherapy in clinical trials. Capecitabine/cisplatin (XP) is one of the standard regimens for the first-line treatment of advanced gastric cancer worldwide. We designed a new regimen combining IP docetaxel (DOC) with XP, and the recommended dose of IP DOC was determined to be 10 mg/m² in a phase I study. A phase II study of XP plus IP DOC was performed in gastric cancer patients with peritoneal metastasis. Methods: Gastric cancer patients with peritoneal metastasis confirmed by diagnostic imaging, laparoscopy or laparotomy were enrolled. DOC was administered intraperitoneally at 10 mg/m² on days 1 and 8. Cisplatin was administered intravenously at 80 mg/m² on day 1, and capecitabine was administered at 1000 mg/m² bid for 14 consecutive days, repeated every 21 days. The primary endpoint was the 1-year overall survival (OS) rate. Secondary endpoints were response rate, negative conversion rate on peritoneal cytology and safety. Results: Out of 50 patients enrolled, 48 patients received protocol treatment, and were evaluated for OS and toxicity. The median number of courses was 6 (range 1-15). The 1-year OS rate was 75% (95% confidence interval, 60-85%). The best overall response was stable disease in all the three patients with target lesions. Cancer cells ceased to be detected by peritoneal cytology in 28 (76%) of 37 patients. Nineteen patients underwent gastrectomy after response to chemotherapy. The incidences of grade 3/4 hematological and non-hematological toxicities were 42% and 48%, respectively. The frequent grade 3/4 toxicities included neutropenia (21%), leukopenia (8%), anemia (29%), anorexia (25%) and nausea (17%). Infection of the intraperitoneal port was observed in one patient. There were no treatment-related deaths. Conclusions: Combination chemotherapy of XP plus IP DOC regimen is well tolerated and active in gastric cancer patients with peritoneal metastasis. Clinical trial information: UMIN000016469.