The authors assessed whether a period of 3 weeks, rather than the commonly used 6 weeks, of smooth Kirschner wire fixation and cast immobilization of the elbow was sufficient to achieve union of displaced fractures of the lateral humeral condyle treated by open reduction. The authors found only one nonunion in a case series of 104 children treated with 3 weeks of fixation. Infections occurred in two children (2%). Late review of 63 children (61%) showed abnormalities of elbow shape in 28 (44%) and wide surgical scars in 43 (68%). The abnormalities of elbow shape were mainly due to overgrowth of the lateral humeral condyle, to the formation of excessive amounts of bone over the outer surface of the condyle, or both. The authors' findings indicate that a period of 3 weeks of smooth Kirschner wire fixation and elbow immobilization is sufficient to achieve healing in most displaced fractures of the lateral humeral condyle treated by open reduction. The findings also indicate that new strategies are needed to reduce the occurrence of overgrowth of the lateral condyle, excessive formation of bone over the condyle, and wide scars.