We reviewed the records of the first forty patients who had been managed at our institution with the Ilizarov technique for the correction of limb deformities, including limb-length inequality, to delineate the complications of this method of treatment. The duration of follow-up ranged from two and one-half to four years. A complication was defined as any untoward occurrence to a patient either during the course of treatment or after removal of the fixator. A major complication was considered one that necessitated an additional operative procedure; caused lasting sequelae, such as malunion, deformation of new bone, joint contracture or stiffness, or nerve palsy; or prolonged the treatment. A minor complication was regarded as one that responded to non-operative treatment and did not cause lasting sequelae, such as transient decreased motion of the joint, paresthesia, or pin-track infection. There were eighty-eight complications--thirty-eight, major, and the remaining fifty, minor--in the sixty-one segments of the limb that were treated; this represented an average of almost one and one-half complications for each segment. Twenty-nine unplanned operative procedures were performed either during treatment with the Ilizarov technique or after removal of the fixator. As anticipated, the prevalence of major complications was highest in the patients who had had more complex and prolonged treatment. Such complications were encountered less often as the surgeons gained experience with the procedure, but the rate of minor complications remained relatively constant, despite the increased experience.(ABSTRACT TRUNCATED AT 250 WORDS)