Peritoneal dissemination with advanced gastric cancer is of significant problem. Peritoneal lavage cytology has been an effective method for the detection of early peritoneal dissemination since 1999. The accurate evaluation of peritoneal lavage cytology is unclear except for the same prognosis of peritoneal dissemination. We examined the clinical findings and the prognosis with positive cases in peritoneal lavage cytology. The prognosis of cases with P1CY1 or P2P3 group was poorer than in the P0CY1 or P0, CY1 group. We thus review the evaluation of peritoneal lavage cytology with gastric cancer in the Japanese and English literature. In addition, we describe the diagnosis of early peritoneal dissemination using peritoneal lavage tumor markers or molecular markers of peritoneal lavage.