Stereoscopic macroradiography was used to study the pattern of union of scaphoid fractures. Of 21 patients who had partial union of a scaphoid fracture, 13 united on the ulnar side and five on the radial side only. In three it was on both sides but delayed in the centre. Where there was initial union on the ulnar side, all progressed to complete union, including two patients with displaced fractures. Four out of five patients with initial union on the radial side had displaced fractures, and three of these went on to non-union. We conclude that in those patients with partial union of a scaphoid fracture, if union is seen on the ulnar side, the fracture is likely to unite completely, whereas if there is partial union on the radial side, there is a high risk of non-union.