This study was designed to examine the effects of dose of recombinant human BMP-2 (rhBMP-2) on bone formation at palatal sites in 10-week-old (10w) and 70-week-old (70w) rats, when combined with a polylactate-polyglycolate copolymer/gelatine sponge (PGS). New bone formation was observed at six weeks after implantation. In the 10w rats, thickness of new bone (TNB) increased as the dosage increased from 0 microg to 4 microg, and decreased significantly as the dosage increased from 8 microg to 24 microg. In contrast, in the 70w rats, TNB increased as the dosage increased from 0 microg to 16 microg, and did not significantly change as the dosage increased from 16 microg to 24 microg. These results suggest that the most effective dosage of rhBMP-2 for induction of bone formation varies according to age.