The hydroxyapatite orbital implant is designed to provide the enucleated patient with improved motility of the prosthesis. We report the results of our first 100 consecutive cases of hydroxyapatite implantation in eyes enucleated primarily for intraocular neoplasms. During a median of 11 months' follow-up, there have been no cases of orbital infection, implant extrusion, or implant migration. Minor postoperative problems have included transient orbital pain in six patients, Tenon's fascia edema and buried peg from tissue overgrowth in two patients each, wound erosion and peg extrusion in one patient each, and audible click of the peg in three patients. Movement of the socket and fornices was excellent in 99% of patients. Motility was cosmetically satisfactory with 10 degrees to 15 degrees rapid darting prosthesis movement present in 96% of patients regardless of whether the peg had been placed. Large-degree prosthesis motility (greater than 15 degrees) was present in 24% of all patients and was most impressive in those adults who had the peg in place and in children. The hydroxyapatite implant appears to be well tolerated and provides prosthesis motility with few problems.