For the first time, this study provides an in-depth analysis of the significant therapeutic aspect of the Isenheim Altarpiece. In the considerations and reflections of the author, Johannes W. Rohen, medical expertise, esoteric background, and a trained eye for composition and iconographic details come together in a fortunate way. Surprisingly, in the extensive literature on Matthias Grünewald's masterpiece, the therapeutic aspect has largely been overlooked. This aspect is undoubtedly essential for both the commissioning abbot of the Antonite monastery in Isenheim, Guido Guersi, and for Grünewald himself. And even if we lack sources that document a practical therapeutic use of the altar for pilgrims suffering from St. Anthony's fire or for the monks caring for them, the Isenheim Altarpiece itself reveals much through its many elements typical of an altarpiece.