The data include the materials for the research article "Genome-wide scan for selective sweeps identifies novel loci associated with resistance to mastitis". The aim of this study was to identify the genomic regions associated with mastitis, using the genotypes from the national project of Holstein dairy cattle in Germany. The samples were ... genotyped with Bovine 50K SNP chip. Based on random residual effects of the mastitis diagnoses, 133 healthy and sick samples from 13290 genotyped dairy cows were selected, respectively. Selection signatures between cows in healthy and sick groups were detected using XP-EHH statistic. Detailed analyses and methods can be found in the article. The data used in this study are presented in the following three files: PhenoMast.txt: Mastitis records of the 13276 genotyped cows. First row includes column names, i.e., cow ID, herd, year-season, mastitis diagnoses. GenoHealth.txt: Genotypes of the 133 healthy cows. First column is cow ID and following 45613 columns are genotypes of the 133 cows (one SNP marker per column). GenoSick.txt: Genotypes from the 133 sick cows. First column is cow ID and following 45613 columns are genotypes of the 133 cows (one SNP marker per column).