Cubitus varus may occur after supracondylar humerus fractures. Poor fixation, however, complicates operative treatment of cubitus varus. We discuss the use of external fixation in the treatment of cubitus varus. Five patients had humeral osteotomies with external fixation. The preoperative humeroulnar angle (HUA) averaged -24.2 degrees. The immediate postoperative HUA averaged 12 degrees, and the final angle averaged 13 degrees. Duration of external fixation averaged 8.9 weeks. Complications were one transient radial neurapraxia, one superficial pin infection, and one keloid. No loss of correction or motion occurred with external fixation; we recommend external fixation as safe and effective.