Fifty-two tibial shaft fractures in 50 patients were treated with flexible medullary nails (Ender type). In 32 cases the fracture was closed and in the remaining 28 cases the fracture was open. Forty-eight of the 52 fractures united in an average time of 16.8 weeks and there were no cases of deep infection or osteomyelitis. Nonunion in four patients required a secondary procedure to obtain union. Flexible medullary nailing is an excellent method for fixation of tibial shaft fractures because it combines the benefits of closed nailing and functional bracing while minimizing the disadvantages of each. Three-point fixation within the medullary canal maintains length alignment and avoids rotational problems. Nailing is done by closed methods without reaming. The technique allows early weight-bearing in a patellar tendon bearing cast or functional brace. Dynamic controlled motion at the fracture site leads to early callus formation which is biomechanically and biologically favorable. The procedure is relatively easy to perform, short in duration, and requires little specialized equipment. Flexible medullary nailing is an alternative treatment modality for selected open and closed displaced tibial shaft fractures.