Samples infected with Monilinia laxa and Monilinia fructigena were collected from different European countries and different plant hosts and fungal strains were isolated (102 x M. laxa, 37 x M. fructigena). In order to determine the baseline sensitivity of these isolates to the newly introduced fungicides pyraclostrobin and boscalid, an appropriate micro-titer assay was developed. For both active ingredients, Yba medium was the medium of choice, since it allowed sufficient growth but did not lead to false positive results. The minimum inhibitory concentrations (Mic) were assessed. Mic values ranged for pyraclostrobin and M. laxa from 0.01–2.5 ppm and for M. fructigena from 0,039–0,625 ppm. For boscalid Mic values were 0.01–2.5 ppm for M. laxa and 0.039–2.5 ppm for M. fructigena.