The aim of the present study was to determine the presence of alkaline phosphatase during various stages in development and closure of the sutura interfrontalis. The histological sections reveal that this enzyme could primarily be demonstrated in the dura mater of this suture. In further developmental stages, alkaline phosphatase could be observed within the intermediate zone as well as the pericranium. These findings are brought in relation with the occurrence of synostosis which can be induced under experimental conditions.