Gastropod shells occupied by hermit crabs are an important attachment substrate for epifauna, and these shells are often damaged. The present study aimed to characterize the epibionts and extent of damage for gastropod shells occupied by the hermit crab Loxopagurus loxochelis (Moreira, 1901). Samples were collected monthly over a period of one year (from July 2002 through June 2003), in the Caraguatatuba and Ubatuba regions, on the northern coast of São Paulo, Brazil. The sampling was performed using a fishing boat equipped with double-rig nets. The shells were identified and weighed. Loxopagurus loxochelis occupied 14 gastropod shell species in Caraguatatuba and five in Ubatuba. In the two areas, approximately 55% of these gastropod shells bore epibionts, and a significantly large number (p < 0.05) showed no damage. The presence of epibionts did not significantly change the mean weight of shells. This cover may provide camouflage to the animals when they are associated with the sandy substrate, which possibly affects the occupancy of the shells by the hermit crabs. Undamaged shells may reflect a high availability of shells in good condition in the environment.