A 54-year-old woman with scirrhous gastric cancer in the upper third area was admitted to our hospital. She was diagnosed with advanced gastric cancer that was inoperable due to peritoneal metastasis, so weekly paclitaxel (PTX) therapy was carried out. After 2 courses, malignant ascites completely disappeared and bilateral hydronephrosis improved. After 4 courses, no ascites or hydronephrosis were seen. Only neutropenia (grade 2) and alopecia (grade 1) were observed as adverse events during the therapy, but no major adverse events were noted. We also investigated the concentration of paclitaxel in ascites. Two hours after intravenous injection of PTX, the concentration of PTX in ascites rose over the reported cytotoxic dose of PTX, and this available concentration was maintained after 48 hours. Weekly paclitaxel therapy is suggested to be one of the safe and useful treatments for advanced gastric cancer with malignant ascites.