Implantation of a synthetic midurethral sling (SMUS) is the most commonly performed anti-incontinence operation in women worldwide. The effectiveness of the SMUS is comparable to that of the historical gold standards--autologous fascial slings and the Burch colposuspension. Much controversy, however, has evolved regarding the safety of this type of sling. Overall, the quality of the studies with respect to assessing risks of SMUS-associated complications is currently poor. The most common risks in patients with SMUS include urethral obstruction requiring surgery (2.3% of patients with SMUS), vaginal, bladder and/or urethral erosion requiring surgery (1.8%) and refractory chronic pain (4.1%); these data likely represent the minimum risks. In addition, the failure rate of SMUS implantation surgery is probably at least 5% in patients with stress urinary incontinence (SUI). Furthermore, at least one-third of patients undergoing sling excision surgery develop recurrent SUI. Considering the additional risks of refractory overactive bladder, fistulas and bowel perforations, among others, the overall risk of a negative outcome after SMUS implantation surgery is ≥15%.