Phytophthora infestans is the fungus causing late blight and is the most devastating fungal disease in potato. It causes considerable losses due to haulm destruction and decay of the tubers. Chemical control is still the most important measure for the control of late blight. To reduce the chemical input in potato we try at KARNA to breed for resistance to late blight. In the early days of potato breeding, the introduction of resistance to phytophthora was focused on single race specific genes, mainly from the wild species Solanum demissum. Nowadays more effort is put in the non-race specific resistance.