Fourteen extension osteotomies were performed in 13 patients with angular metacarpal malunion. Surgery was indicated by the limitation of mobility, the reduction in gripping capacity, and pain following digitopalmar grasping movements. After surgery, the patients regained good articular mobility. However, in 60% of cases a teno-arthrolysis was required upon removal of consolidation hardware to restore digital function. The operation allowed pain relief in two-thirds of the patient population; in the remaining subjects, pain was experienced when making grasping movements. At the final examination, in the majority of cases gripping strength was similar to that of the contralateral hand. In conclusion, correction of angular malunion by extension osteotomy is a demanding procedure, and whenever possible should be avoided by a precise reduction of the metacarpal fracture during initial surgery. A fractured metacarpal with a palmar angulation of over 15 degrees should systematically be reduced and fixed if unstable.