Introduction. Midcarpal instability is an uncommon but troublesome problem. Patients have loss of dynamic control of the wrist in pronation and ulnar deviation due to laxity of the volar wrist ligaments that is often congenital or due to minor trauma. For those in whom conservative measures fail, open ligament reconstruction or fusions have been described. Aim. We prospectively studied a series of fourteen patients who underwent arthroscopic thermal capsular shrinkage for midcarpal instability. Methods. All patients were assessed clinically and by fluoroscopy and arthroscopy to confirm the diagnosis. Wrist arthroscopy with four portals was performed and monopolar radiofrequency capsular shrinkage was performed using a 2.3mm probe. Post-operatively the wrist was immobilised in a splint for 6 weeks. Results. Fourteen wrists in eleven patients were treated. Mean length of follow-up was 44 months. Symptoms of instability never occurred in three wrists and rarely occurred in eleven. The patient's subjective overall assessment of the wrist was ‘much better’ in ten wrists, ‘better’ for one wrist and ‘worse’ for three wrists. These three cases had persistent pain but improvement of instability symptoms. Two of these cases belonged to the same patient who had Ehlers Danlos syndrome. All patients were satisfied with the outcome and would have the same procedure again. The mean pre-operative DASH score was 35.2 and 17.1 at the most recent follow-up. Mean flexion decreased by 25% and mean extension by 17%. There were no significant complications. Conclusion. Capsular shrinkage is an effective procedure for midcarpal instability. Although there are some concerns regarding deterioration of results over time as seen in shoulder instability, these mid-term results show that this is currently not a problem