AIM: To compare the exposure rate, infection rate, percentage of enhancement, and success rate between Medpor and the three-dimensional printed polyethylene (3DP-PE) orbital implant in a preliminary report. METHODS: This prospective, randomized, equivalence, controlled trial was conducted at two institutes. The equivalent margin was ±10%. The sample size for the equivalence trial was 174 participants per group. Patients who were eligible for enucleations received either Medpor or 3DP-PE implants based on a randomized block of six. The surgeries were performed by five oculoplastic surgeons. The assessor and patients were masked. The magnetic resonance imaging (MRI) of the orbit was performed at least 6mo after operation and the fibrovascular ingrowth was analyzed using the Image J software. Follow-up continued at least 1y after surgery. The intention to treat and per protocol approaches were used. RESULTS: Totally 128 patients met the criteria in the report. Fifty Medpor and 55 3DP-PE cases completed the trial. The most common cause of blindness was trauma. The mean follow-up times of Medpor and 3DP-PE were 33 and 40mo respectively. The exposure rate was not statistically significant between two groups (6.0% and 7.3%), P<0.05, 95%CI (-9.8%, +12.0%). The success rates were 94% (Medpor) and 92.7% (3DP-PE). No postoperative infection was reported. Nine patients had MRI tests and two had implant exposures with 66.3% enhancement at 75mo (Medpor) and 58% enhancement at 57mo (3DP-PE) postoperatively. CONCLUSION: There is no statistically significant difference in exposure rate and success rate between Medpor and 3DP-PE in enucleation in the report. However, we cannot conclude that they are equivalent in terms of the exposure rate and success rate because the 95%CI is wider than ±10%. The infection rate is equivalent in both groups.