Purpose: Dermatofibrosarcoma protuberans is a relatively rare tumor that originates from the dermis and subcutaneous tissue. It is generally known that this tumor easily recurs but can be successfully treated with a wide excision. Therefore, this study was conducted to investigate postoperative outcomes and risk factors for recurrence in patients with dermatofibrosarcoma protuberans who were treated at a single institution for 20 years. Methods: We retrospectively reviewed the medical records of 35 patients who had underwent surgery between June 1992, and September 2010. The patients were assessed in terms of predilection site and size of the tumor, the incidence according to sex, discrepancy between biopsy results and histopathological diagnosis of the surgical specimen, additional treatment after recurrence, recurrence rate and the time interval to recurrence. Results: In multivariate analysis, the depth and site of the tumor were significant risk factors for tumor recurrence. The recurrence rate was significantly higher in tumors occurring in the upper extremity than those occurring in other regions ($p$=0.0348). In addition, the recurrence rate was significantly higher in tumors with involvement of the fascia and the deeper structures ($p$=0.0324, odds ratio=6, relative risk=1.588). Since dermatofibrosarcoma protuberans has strong invasiveness, its tissue involvement is difficult to evaluate accurately. Conclusion: The results of this study shows that involvement of the fascia and the deeper structures and occurrence in the upper extremity were associated with tumor recurrence. Therefore, clinicians should be aware of these risk factors to achieve better treatment outcomes.