Regeneration of artificial lesions (simulating damage by predators and physical factors) on the living surfaces of the corals A. agaricites- f. purpurea- and P. astreoides- was studied in situ at 25 and 18-23 m, respectively. Porites- regenerated ca 50% of 1 cm^-2 lesions completely, Agaricia- less than 10%. Larger, 5 cm^-2, lesions were not re-covered by either species in the 140 days of observation. The results demonstrate the vulnerability of some corals to mechanical damage and illustrate species-specific characteristics.