Objective: To evaluate the efficacy and safety of an acellular xenogenic dermal matrix (AXDM) as a spacer graft in the surgery to treat upper and/or lower eyelid retraction (UER/LER) in patients with thyroid associated ophthalmopathy (TAO). Methods: This was a retrospective case series study. From January 2016 to December 2017, all the TAO patients who underwent the eyelid retraction surgery with an AXDM as a spacer graft in Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine were included in the study. The follow-up duration was at least 6 months. Eyelid height, ocular discomfort symptoms, and complications were recorded and used to evaluate the efficacy and safety. The treatment outcomes were divided into good, acceptable and unacceptable outcomes. Nonparametric test was used to compare the efficacy of upper and lower eyelid surgery. Results: Eighty patients (102 eyes) were included, consisting of 43 patients (56 eyes) with UER and 37 patients (46 eyes) with LER. The UER patients included 34 females (median age, 37 years) and 9 males (median age, 47 years). The LER patients included 20 females (median age, 39 years) and 17 males (median age, 40 years). At 6 months after surgery, ocular discomfort was relieved in 79.0% (64/81) eyes; photophobia was relieved in 69.5% (41/59) eyes; tearing was relieved in 94.9% (37/39) eyes; lagophthalmos was relieved in 80.7% (67/83) eyes. In patients with UER, the margin reflex distance was lowered from 8.0 (7.5, 8.0) mm to 3.5 (3.4, 4.0) mm (Z=-6.587, P<0.01). The upper scleral show was lowered from 3.0 (3.0, 3.5) mm to 0 mm (Z=-6.616, P<0.01). In patients with LER, the margin reflex distance was lowered from 8.5 (7.5, 9.0) mm to 5.5 (5.5, 6.0) mm (Z=-5.979, P<0.01). The lower scleral show was lowered from 3.0 (2.5, 3.5) mm to 0.0 (0.0, 0.5) mm (Z=-5.965, P<0.01). In total, 71.3% (57 cases) of the patients acquired good outcomes, 22.5% (18 cases) acquired acceptable outcomes, and 6.3% (5 cases) had recurrence, and no significant difference was found between the patients with UER and LER (33, 8, 2 cases vs. 24, 10, 3 cases, Z=-1.176, P>0.05). No other complications, such as infection, rejection, and dislocation, were observed. Conclusion: AXDM as a spacer graft can be a reasonable and safe alternative for eyelid retraction in TAO patients, achieving both the functional and aesthetic improvements. (Chin J Ophthalmol, 2019, 55: 821-827).