Despite the popularity of surgical repair of rotator cuff tears, literature regarding the indications for and timing of surgery are sparse. We performed a systematic review of the literature to investigate factors influencing the decision to surgically repair symptomatic, full-thickness rotator cuff tears. Specifically, how do demographic variables, duration of symptoms, timing of surgery, physical examination findings, and size of tear affect treatment outcome and indications for surgery? We reviewed the best available evidence, which offers some guidelines for surgical decision making. Variables suggest earlier surgical intervention may be needed in the setting of weakness and substantial functional disability. With regard to demographic variables, the evidence is unclear regarding their association with treatment outcome. However, older chronological age does not seem to portend a worse outcome. Pending worker's compensation claims does seem to negatively affect treatment results. Further research is required to define the indications for surgery for full thickness rotator cuff tears. However, the design and conduct of an ethical study to obtain Level I evidence on this issue will be a major challenge.