Eighty-two athletes with 86 clinical navicular stress fractures, all imaged with computerized tomography, were followed for an average of 33 months (range, 6 to 108) after diagnosis. Initial treatment consisted of at least 6 weeks of nonweightbearing cast immobilization for 22 fractures, at least 6 weeks of limitation of activity with continued weightbearing for 34 fractures, and a period of less than 6 weeks of conservative treatment for another 19 fractures. Five patients attempted to continue playing sports. Six patients had immediate surgery. Nineteen of 22 patients (86%) who had initial non-weightbearing cast immobilization treatment returned to sports, compared with only 9 of 34 patients (26%) who initially continued weightbearing with limited activity (P < 0.001). After failure of the latter treatment, successful outcomes were seen for 6 of 7 patients (86%) treated with nonweightbearing cast immobilization, while 11 of 15 patients (73%) who had one surgical procedure were able to return to sports. These results indicate that nonweightbearing cast immobilization is the treatment of choice for navicular stress fractures. Also, this treatment compares favorably with surgical treatment for patients who present after failed weightbearing treatments. Computerized tomographic appearances of healing fractures do not necessarily mirror clinical union, and postimmobilization management should be monitored clinically.