OBJECTIVE We conducted a study to evaluate the long-term functional outcomes of patients with an isolated tibial shaft fracture treated with locked intramedullary nailing. METHODS Prospective cohort and retrospective clinical and radiographic assessment. METHODS A level 1 trauma and tertiary referral center. METHODS We identified 250 eligible patients with isolated tibia fractures from the Center's prospectively enrolled orthopaedic trauma database between 1987 and 1992. A total of 56 patients agreed to participate. We had a median follow-up of 14 years, with a range from 12 to 17 years. METHODS All enrolled patients were initially acutely treated with locked intramedullary nailing of their tibia. METHODS All enrolled patients were evaluated with the SF-36 and Short Musculoskeletal Functional Assessment functional questionnaires and an injury-specific questionnaire focusing on knee pain and symptoms of venous insufficiency. A subgroup of patients were evaluated radiographically and by physical examination. RESULTS The mean normalized SF-36 scores (physical composite score-PCS 48.9, mental composite score-MCS 51.8) and the mean normalized Short Musculoskeletal Functional Assessment scores (50.7) (bothersome index, functional index) were not statistically different (P > 0.05) from reference population norms. Of the questionnaire group (n = 56), only 15 (26.7%) denied knee pain with any activity whereas 41 patients (73.2%) had at least moderate knee pain. With respect to swelling, 19 (33.9%) reported asymmetrical swelling affecting the injured limb. However, of the 33 physically examined patients, only 6 (18.2%) had objective evidence of venous stasis. Knee range of motion was equivalent to the unaffected side in all but two patients (93.9%) whereas 14 (42.4%) had a restricted range of motion of the ankle. Nine patients (27.3%) had persistent quadriceps atrophy, and the same rate was observed for calf atrophy. Twenty-five patients (75.8%) had no tenderness to anterior knee palpation. Of the 31 radiographically examined patients, 11 patients (35.4%) showed evidence of arthritis despite the absence of radiographic malalignment. Five patients (16.1%) had at least mild osteoarthritis of at least one knee compartment, 5 (16.1%) had at least mild osteoarthritis of the tibio-talar joint, and 1 (3.2%) had osteoarthritis of both, despite the absence of malunion. Self-reported knee pain was not correlated with the presence of a tibial nail or radiographic nail prominence. Similarly, knee tenderness on examination was not correlated with these factors. CONCLUSIONS At a median 14 years after tibial nailing of isolated tibial fractures, patients' function is comparable to population norms, but objective and subjective evaluation shows persistent sequelae which are not insignificant. This study is the first to describe the long-term functional outcomes after tibial shaft fractures treated with intramedullary nailing nails. It may allow surgeons to better inform patients on the expected long-term function after intramedullary nailing of a tibia fracture. It may also prove useful when comparing intramedullary nailing nailing to other treatment techniques.