Purpose: The purpose of this study is to find out the clinical results of excision of the Os trigonum through a posterolateral approach and to compare the surgical results of athletes with non-athletes. Materials and Methods: Within a five year and four month period, from July 2001 to October 2006, twenty patients underwent excision of symptomatic os trigonum, with a mean age of 22 years and 9 months at the time of the operation. There were fifteen female patients and five male patients. Eight were athletes and twelve were non-athletes. Results: The average duration of postoperative follow-up was thirty months. The postoperative AOFAS scored an average of 89 points compared to the preoperative AOFAS scored an average of 67 points. Sixteen patients (80%) who were operated, had good or excellent satisfactory results. The average preoperative AOFAS score of the athletes were 61 points, compared to the average postoperative AOFAS score of 90 points. For non-athletes, the average preoperative score was 71 points, compared to the average postoperative AOFAS score of 88 points. Seven athletes (87%) and nine non-athletes (75%) had good or excellent satisfaction results after surgery. The time until full recovery averaged 88 days for all the patients. 133 days for the athletes and 56 days for the non-athletes. There is no analytic difference between result in athletes and result in non-athletes. Conclusion: Open surgical treatment through posterolateral approach of os trigonum syndrome of the ankle may be effective modality regardless of the patient being an athlete or non-athlete.