An original technique was developed to correct distal humerus malunion using a three-dimensional computer-assisted planning and a custom-made surgical guide. The technique was used in three cases (two with cubitus varus and one with cubitus valgus).A CT-scan of the distal humerus was obtained. The correction was simulated by software. A three-dimensional model of the patient's affected humerus was created by rapid prototyping, allowing creation of a surgical guide and premoulding of the osteosynthesis plate. At the time of surgery, the sterilised guide was placed on the surface of the bone to guide the saw blade. Osteosynthesis was performed using the moulded plate. At the latest follow-up, all three patients were asymptomatic and had regained full elbow mobility. Satisfying correction was obtained in all three cases. One complication was encountered: a postoperative infection that healed with plate removal and systemic antibiotic administration. Using an osteotomy guide facilitates three-dimensional humeral correction. This technique presents several benefits: it decreases the operating time and minimizes the surgical incision. Fluoroscopy is unnecessary during the procedure and accuracy is increased. Disadvantages are the time for planning and guide confection, the need of a CT-scanner and the increased cost.