Polymyositis (PM) and dermatomyositis (DM) are rare diseases. There are few randomized controlled trials for the immunosuppressive therapy. We analysed 112 therapeutic cycles from 63 patients of Halle’s university hospital with following diagnoses: PM and Jo-1-syndrome (33), DM (23), Overlap-syndrome (4) and non-classified myositis (3). All drug groups are showing a significant effect (p<0005) on CK improvement. Within the drug groups we found significant CK improvements for MTX, Azathioprine, combination therapies, first- and third line therapies. Furthermore we have demonstrated a significant effect for muscle strength improvement for MTX, Azathioprine, and first line therapy. Our base data confirm results of epidemiological studies. In our trial, the immunosuppressive drugs MTX and Azathioprine were often used, and have proved quite efficient in the therapeutic strategies. The other drugs should be used in advanced disease stages; and combination therapies in refractory diseases.