By using photoacoustic (PA) spectroscopy it was performed a study about bone consolidation in fractures. It was obtained the optical absorption spectra of callus of male rat fractured bones at different consolidation times. From these spectra it was possible to observe the presence of alkaline phosphatase through their absorption peaks which were compared with characteristic peaks reported in the literature for this phosphatase. In this study we showed that alkaline phosphatase could be considered as an indicator of the repair process of bone fractures.