Fluence-dependent sputtering of implanted projectiles and target material atoms is investigated by means of Monte Carlo simulation for the bombardment of materials with 30 keV Ga+ ions. During the bombardment, the target atom sputtering yield decreases, except for low atomic number (Z(2),) materials, and the target surface is less eroded than for no implantation of the projectiles. For low Z(2) materials (Be and C) the target atom sputtering yield increases due to shallow collision cascade in a mixed layer, furthermore, the transition from deposition to strong erosion is calculated during the bombardment. Thermal diffusion of the implanted projectiles increases (decreases) the implanted (target) atom sputtering yield due to the increase in their retention in the near-surface zone. (C) 2002 Elsevier Science B.V. All rights reserved.