Hidradenitis suppurativa (HS) is a rare, debilitating skin disease characterized by the presence of recurrent tender subcutaneous nodules that develop into abscesses and fistulae. Isolated perineal Crohn's disease (CD) is unusual, diagnosis can be difficult, and distinction from HS is a challenge for the gastroenterologist. The aim of this work was to determine the criteria that distinguish perineal CD from perineal HS. Four patients with isolated perineal CD and three with perineal HS were included. Rectal or skin biopsies of all CD patients showed granulomas. No granulomas were found for HS. Fistulae were present in 4/4 CD, extended to the anal canal. All patients with HS had gluteal abscesses. They were bilateral in all cases, superficial. Perineal lesions management should involve a multidisciplinary approach in order to make an accurate diagnosis and ultimately to give the best and most effective treatment.