To evaluate the effect of patient- and tooth-related factors on the outcome of apical surgery in a multicenter study. A total of 281 teeth in 255 patients undergoing periradicular surgery were investigated clinically and radiographically 6 to 12 months postoperatively. The overall success rate was 88.0%. Sex was a significant (P = .024) predictor, with a success rate of 89.8% in females and 84.0% in males. The success rate was significantly higher in patients 31 to 40 years of age. The treatment of premolars resulted in a significantly higher success rate (91.9%) than the treatment of anterior teeth (86.1%, P = .042) and molars (86.4 %, P = .026). The loss of the buccal bone plate and the extension of apical osteolysis to the furcation area in molars resulted in a considerably lower success rate. Lesion size, preoperative pain, tenderness to percussion, fistula, and resurgery were significant factors. There are several factors influencing the success rate of apical surgery that must be taken into account when considering apical surgery as a treatment alternative.