Eighty cases of supracondylar fracture of the humerus at the elbow in children have been analysed. The post-reduction radiograph of the fracture was classified depending on the residual deformity present and related to the loss of carrying angle and cubitus varus deformity at the time of follow-up. Fifty-four percent of the displaced fractures showed a loss of carrying angle greater than 5 degrees, and of these 23 per cent developed cubitus varus deformity. Eighty-five per cent of those cases with a loss of carrying angle greater than 10 degrees showed either residual tilt or medial rotation on the post-reduction radiograph. All cases in which there was residual medial tilt after manipulation and 40 per cent of those with medial rotation on the post-reduction radiograph developed cubitus varus. In our series, there was no evidence of epiphyseal injury causing the deformity and in none of the cases was the deformity progressive. It is suggested that, in order to reduce the incidence of varus deformity in suprocondylar fractures, open reduction and internal fixation is indicated in those fractures in which tilt or medial rotation cannot be reduced by conservative means.