Purpose: Peritoneal carcinomatosis (PC) has a dismal prognosis and is occasionally encountered during initial exploration in patients with gastric cancer. The clinicopathological characteristics and survival were analyzed in patients with gastric cancer and PC. Materials and Methods: Among 2,083 gastric cancer patients who received surgery at the department of surgery, Hanyang University Hospital from 1992 to 2009, 130 patients revealed PC. Ten patients who were lost during follow-up were excluded. The remaining 120 patients were divided into three groups according to the type of surgery. The degree of PC was classified into P1(to the adjacent peritoneum) and P2 (to the distant peritoneum). Various other clinicopathological factors were analyzed using univariate and multivariatec survival analyses. Results: Systemic chemotherapy (SC), type of surgery, lymph node dissection, degree of PC, and presence of ascites were significant prognostic factors. However, age, gender, resection of PC, and Borrmann type were not significant prognostic factors. In a multivariate analysis, SC and the degree of PC were independent prognostic factors. The survival benefit of SC was significant without reference to the type of surgery or degree of PC. Conclusions: A gastrectomy should be considered feasible in patients with gastric cancer and PC. The independent favorable prognostic factors were SC and a low degree of PC. SC improved the prognosis regardless of operation type and degree of PC.