Objective To evaluate the roles of 3D-printed porous Ti-6A1-4V cages and polyetheretherketone (PEEK) cages in vertebral fusion in a preclinical sheep model. Methods Cervical anterior diskectomy was conducted in 18 mature female Small Tail Han sheep which were randomized into 2 even groups.3D-printed porous Ti-6A1-4V cages were implanted into 2 levels of cervical disc (C3-4 and C4-5) in the experimental group (n = 9) and PEEK cages (plus bone autograft) in the control group (n=9). Each time at 3 months and 6 months after surgery, 3 animals in each group were sacrificed for X-Ray, Micro-CT and histological examinations to measure bone volume fraction (BVF), mineralized bone fraction (MBF) and bone apposition (BA) in the cage. At 6 months, the remaining 3 animals in each group were sacrificed for biomechanical analyses to measure range of motion (ROM) of the lower vertebral body relative to the upper vertebral body under the maximum moment. Results X-Ray and Micro-CT evaluations showed that all cages obtained complete fusion at 6 months. A rapid ingrowth of bone tissue into the 3D-printed porous Ti-6Al-4V cages was found. At 3 months, BVF in the experimental group (27.1%±3.7%) was significantly lower than in the control group (37.6%±8.2%) (P 0.05). Histological evaluation showed that the bone tissue in the pores bound closely with the Ti alloy to form intimate bone-material connection. At 3 months, MBF in the experimental group (22.2%±3.2% ) was significantly lower than in the control group (34.3%±5.0%) (P 0.05). At 3 and 6 months, BA was respectively 10.6%±2.1% and 59.5%±8.6% in the experimental group, showing significant differences from those in the control group (4.6%±2.0% and 5.8%±3.6% respectively) (P < 0.05). At 6 months, ROM of the fused segment in the experimental group was significantly smaller than that in the control group (P < 0.05) . Conclusions In the sheep model of cervical anterior fusion, porous Ti-6Al-4V cages fabricated by 3D printing can achieve rapid bone ingrowth. In addition, since they demonstrate better bone-material integration and mechanical stability than PEEK cages, they have a great potential for clinical application. Key words: Spinal fusion; Ethers; Titanium alloys; 3D printing technology