The authors report the influence of periosteum on healing of palatal defect based on more than 10 years of experience of harvesting hard palate mucosa. Between June of 1991 and May of 2001, the authors harvested 80 hard palate mucosae as graft material for skin and mucosa defects. All grafts were harvested from the center of the hard palate. Patients ranged in age from 10 to 82 years old. Of 80 mucosae, 54 were harvested with periosteum, and periosteum was not retained in the defect bed. The other 26 mucosae were harvested without periosteum, which was therefore retained in the defect bed. The healing time increased depending on the defect size in both groups of patients retaining and not retaining periosteum. There was a significant relationship between the defect size and healing time in both groups (Spearman's rank correlation test,p< 0.0001 in both groups). In the two groups, there was no significant relationship between patient age and healing time in the patients with defect smaller than 1.99 cm2or larger than 2.00 cm2. There were no significant differences in the rate of patients with pain and bleeding between the groups retaining and not retaining periosteum. In the group not retaining the periosteum, all 54 patients showed a flat or atrophic smooth surface at more than 6 months after epithelization and had no discomfort. However, 17 patients showed flat or atrophic smooth surface in the group retaining the periosteum and the remaining 9 patients showed hypertrophy at more than 6 months after epithelization, with accompanying discomfort. The rate of the patients with hypertrophy in the group of patients retaining periosteum was significantly high as compared with that in the group of patients not retaining periosteum (p= 0.000013, Fisher's exact test). In 26 patients retaining periosteum, the age of the patients with hypertrophic surface was significantly younger than that of the patients with flat or atrophic surface (p= 0.0010, Welch'st-test), and the defect size in the patient with hypertrophic surface was significantly smaller than that of the patients with flat or atrophic surface (p= 0.0028, Welch'st-test). In conclusion, our study demonstrated that the existence of periosteum in the palate donor bed does not contribute to reduced healing time or reduced pain. Rather, retaining the periosteum caused hypertrophy of the donor site, leading to discomfort, especially in young patients with a comparatively small defect.