Biodegradability of new types of polyglycolic acid (PGA)-collagen composite tubes for nerve regeneration was evaluated in the peritoneal cavity. Hollow PGA mesh tubes were coated with atelocollagen solution, dried at room temperature, and then subjected to dehydrothermal treatment (hollow composite tubes). Hollow composite tubes filled with collagen sponge were also investigated in this study (sponge tubes). Tubes were fixed at the parietal peritoneum of BALB/c mice, and excised 0.5, 1, 2 and 3 months after the insertion. The inner areas of the excised tubes were measured microscopically. The rate of remained inner areas were calculated and analyzed statistically by one-way ANOVA and Fisher's PLSD test. 1 month after the insertion, the inner areas of the sponge tubes were well maintained, though they were not maintained in the hollow composite tubes. The rate of remained inner areas of the sponge tubes was significantly larger than that of the hollow composite tubes until 2 months after insertion. These results suggest that sponge tubes are more suitable than hollow composite tubes for nerve regeneration in the peritoneal cavity.