Tibial shaft fractures are common injuries. Surgical stabilization using interlocking nails is a popular treatment. Difficult to predict complications such as delayed union or nonunion result in significant disability. We performed a prosprctive study in 15 patients to monitor tibial fracture healing following static interlocking nailing by high resolution ultrasound. Ultrasound correctly prediced fracture in all 8 patients whose fractures subsequently healed. Of the 7 patients in whom a delayed union developed, ultrasound correctly identified delayed healing in all 7 patients. Ultrasound predicted fracture healing sooner at an average of 42 days (range, 28-84 days) than plain radiographs at an average of 119 days (range, 56-196 days. These preliminary results suggest that ultrasound provides important prognostic information about tibial fracture healing after interlocking nailing.