The virulence frequency of 750 wheat powdery mildew isolates of wheat genotypes, carrying 23 Pm-genes and gene combinations, was studied over ten consecutive years from 2004 to 2013. Seventy-eight previously known and 39 new pathotypes were identified during this period. The results indicate that the majority of Pm-genes have high level of virulence. Sixty to ninety percent of the isolates were virulent to Pm6, Pm8, Pm8+11, Pm2+4b+8, Pm3g, Pm10+15, Pm10+14+15. The virulence frequency was variable for Pm1a, Pm2, Pm3a, Pm3b, Pm3c, Pm5, Pm7 genes and reached high level in certain years. The virulence frequency to genes Pm20, Pm37, Pm4a+ and to gene combination with Pm3c+5a+35 and breeding lines CN240/06, CN98/06 and CN158/06 ranged from 1 to 8%. Bread wheat lines CN240/06, CN98/06 and CN158/06, derived from interspecific crosses, proved to be highly resistant to powdery mildew.