Objective To evaluate the clinical effect of Medpor ( porous high density polyethylene )as a padding material in correction of sunken eyelid after hydroxyapatite (HA) implantation. Methods We used Medpor in 17 patients ( 10 male and 7 female ), aged from 18 to 43 years (mean 26.6 years ), in which 9 cases had concomitant orbital fractures. The Medpor was implanted after HA sphere implantation ranged from 2 to 19 months ( average 6.7 months ). 17 consecutive patients with implantation of HA sphere were filled with Medpor under the periosteum. All of the cases were examined by CT scanning to distinguish orbital lesions with or without fracture. In the orbital fracture cases, we first repaired orbit bone defects with Medpor. Results There were no secondary infection or implant rejection occurred after following up for 1 to 18 months (average 8.7 months ). All patients' cosmesis was acceptable. 14 of 17 patients gained symmetric appearance. Although 3 patients had slight sunken eyelid, they gained a dramatic improvement of facial appearance nevertheless. Conclusions Sunken eyelid after HA sphere implant is related with orbital fracture as well as relative reduction of orbital content. Medpor presents fine biological compatibility. It is also easy to remodel and fix during operation. Medpor is a good implant for treatment of sunken eyelid after HA sphere orbital implantaion. [