Aims: Posterolateral rotatory instability of the elbow is believed to express dysfunction of the lateral collateral ligament complex. The purpose of this study was to determine the long-term results of lateral ligamentous reconstruction in patients with posterolateral rotatory instability of the elbow. Methods: From 1986 to 1999, forty-þve consecutive elbows with posterolateral rotatory instability were treated by direct repair of the lateral ligament complex (twelve cases) or augmented reconstruction with a tendon autograft (thirty-three cases). One patient was lost to follow-up one year postoperatively. The remaining forty-four patients were followed for an average of six (range, two to þfteen) years. Results: Surgery initially restored elbow stability in all but þve cases, two of which became stable after a second procedure. At most recent follow-up, three of the forty-þve patients had persistent instability. The most recent mean Mayo Elbow Performance Score was eighty-þve points (range, sixty to 100 points). According to the rating system of Nestor et al., the result was excellent in nineteen, good in thirteen, fair in seven and poor in þve cases. Thirty-eight patients (86 per cent) were subjectively satisþed with the outcome of the operation. Better results were obtained in patients with a postraumatic etiology (p=0.03), subjective complains of instability at presentation (p=0.006), and augmented reconstruction using a tendon graft (p=0.04). Conclusions: Lateral ligamentous reconstruction is an effective long-term procedure for posterolateral rotatory instability. Reconstruction using a tendon graft seems to provide better results than ligament repair. The results of ligamentous reconstruction do not seem to deteriorate with time.