The effect of composting and pasteurization on the quarantine pests of potato Clavibacter michiganensis ssp. sepedonicus (Cms) and Synchytrium endobioticum (Se) were examined on an experimental scale. Composting was performed with 2-L pots and 60-L composters for two months at temperatures below 50 degrees C and for 12 and 21 days at temperatures above 65 degrees C. Pasteurization was performed via water bath at 70 degrees C for maximum 2 hours. Pathogens were introduced directly or via carriers into the processes. After composting for two months and for 12 and 21 days it was possible to isolate vital Cms cells from bioassay plants and vital resting spores of Se could be extracted from sample material. Likewise it was possible to isolate vital Cms cells and resting spores of Se after pasteurization for up to two hours. Both pests could not be killed completely during the performed processes. Further studies concerning sanitization of potato wastes are necessary.