The glass transition behavior of several Zr- and Mg-based metallic glasses has been studied by temperature-modulated differential scanning calorimetry (MDSC). It is clearly demonstrated that the glass transition can be separated from crystallization for these glasses by MDSC. Some glass transitions that could not be observed by a conventional differential scanning calorimetry (DSC) have been detected. Furthermore, the complex change of the heat capacity of the samples during the glass transition and crystallization can now be determined for the first time in one single run.