Objective: In advanced gastric cancer (AGC), peritoneal metastasis (PM) is associated with poor prognosis and worse performance status (PS), which makes chemotherapy administration difficult. However, PM can present with many different clinical pictures. The aim of this study was to investigate the benefits and toxicity of taxane addition to platinum-fluoropyrimidine combination in clinically poor (CPPG) and good prognostic groups (CGPG) of AGC patients with PM. Material and Methods: A total of 172 AGC patients with PM who were treated with taxane plus platinum plus fluoropyrimidine (TPF) or platinum plus fluoropyrimidine (PF) were included in the study. The patients with massive ascites or PS 2-3 or inadequate oral intake were included in the CPPG group, while those with an absence of these clinical factors were included in the CGPG group. The efficacy and toxicity of dose intensity on survival were evaluated separately for each group using the Kaplan-Meier method. Results: At the baseline, 16.9% of all patients had massive ascites, 30.2% had PS of ≥2, and 33.7% had inadequate oral intake. Accordingly, 50.6% of the patients were in CPPG. The overall survival times were found to be similar in patients treated with TPF as well as those treated with PF. Moreover, the addition of taxane treatment did not have any effect on either the poor prognostic group or the good prognostic group. However, as the dose intensity was increased, the grade 3/4 toxicity, dose delay, and reduction rates also increased. Conclusion: Addition of taxane to PF did not contribute to survival in AGC patients with peritoneal metastasis, independent of the clinical prognostic group.