Gemcitabine enhances the cisplatin-induced inhibition of intra-abdominal dissemination. Athymic nude mice were inoculated i.p. with Caov-3 cells. Two weeks after the inoculation of Caov-3 cells, as described in the Materials and Methods section, the athymic mice were randomly assigned to one of four groups treated with different regimens for six weeks. (A) Physical appearance of representative mice. The combination of Cisplatin and Gemcitabine reduced the production of ascites (I) and intra-abdominal dissemination (II and III). (B) Magnified views of the intra-abdominal dissemination pattern in the vehicle mice and histological findings (×200 magnification) of hematoxylin and eosin staining of parietal peritoneal dissemination in the athymic nude mice. (C) Relative ratios of the abdominal circumferences in each group. The combination of Cisplatin and Gemcitabine significantly decreased the mean abdominal circumference six weeks after the initiation of treatment. Significant differences are indicated by asterisks. **p < 0.01, *p < 0.05.