Hidradenitis suppurativa (HS) is a chronic inflammatory skin condition characterized by swollen, painful, inflamed lesions in the axillae, groin, armpits and other parts of the body that contain apocrine glands. The aetiology of HS is unknown, and earlier reports indicate genetic locus responsible for this phenotype on chromosome 1p21.1-1q25.3, but no causative gene(s) have yet been identified. We studied two large multigeneration pedigrees (UR251 and UR252), in which the condition appeared to segregate as an autosomal dominant trait with 100% penetrance. No skipping of generations was observed in either family. Pedigrees consist of 96 individuals, including 25 affected individuals. Because of squamous cell carcinoma, a few deaths were reported in family UR0251. The locus on chromosome 1p21.1-1p25.3, known from previous studies is associated with HS, was excluded in both families by linkage and haplotype analyses. Further studies are in progress to identify the region that is associated with the phenotype in these families.