Alkaline phosphatase (ALP) and bone-specific alkaline phosphatase (S-bone ALP) activities may serve as markers of the course and rate of bone healing after sustained fractures. The aim of this study was to examine whether the assessment of S-bone ALP as a biochemical parameter in the early posttraumatic phase may indicate the course of fracture healing. To date, the methods used to monitor the bone healing process have been based on the patients' assessment and the radiographic findings. In view of the fact that patient opinion is highly subjective, that the radiographic findings depend on the radiologist's experience and that the monitoring of bone healing is a long-lasting process, measurements of biochemical parameters appear to be the only objective evidence of the changes occurring during bone regeneration. In this study, the activity of bone-specific alkaline phosphatase was measured in the serum of 41 patients who had sustained long bone fractures. The participants included 26 males and 15 females, aged 15 to 80 years. All patients were treated surgically. The activity of S-bone ALP was assessed every seven days over a period of 4 weeks. The study patients were followed up radiologically for several months. Our research showed that the increase of alkaline phosphatase correlated with an increase of S-bone ALP levels. In addition, changes in ALP levels on days 7 and 14 as compared to those on day 1 post injury were associated with changes in S-bone ALP levels on the same day. Likewise, the callus volume correlated with the decrease, no change or increase in the levels of ALP and S-bone ALP in the same way. Based on these results, it may be concluded that monitoring changes in the biochemical parameters alkaline phosphatase and bone-specific alkaline phosphatase allows early detection of fracture healing rates. A minor increase in the activity or no change in the level of the biochemical parameters ALP and S-bone ALP in the period of the first two weeks indicates successful fracture fixation, rapid bone healing and the formation of a minimal or insignificant callus. A major increase in the activity of the biochemical parameters ALP and S-bone ALP in the period of the first two weeks indicates inadequate fracture fixation, delayed bone healing and the formation of a visible and significant callus.