Background: Pemphigus vulgaris (PV) is an autoimmune blistering disease, caused by autoantibodies against desmoglein (Dsg) 3 and / or Dsg1 which induce the loss of adhesion between keratinocytes. Nikolsky's sign is the ability to induce peripheral extension of a blister as a consequence of applying lateral pressure to the border of an intact blister. If the weakening of the intercellular adhesion is present but not marked, then the damage may be demonstrated only microscopically (microscopic Nikolsky’s sign and can increase the sensitivity of the histopathological studies. Methods: We studied 40 patients and divided them randomly into two groups (A, B). Group A were subjected to the tangential pressure over the perilesional skin before a biopsy specimen was taken from that site; group B patients were subjected to a biopsy without the tangential pressure technique. Results: Histopathological changes of pemphigus vulgaris were present in 30% of the patients in group A and 5% of the patients in group B. They were not statistically different. The presence of microscopic Nikolsky’s sign was significantly higher in patients with generalized disease. Conclusion: Microscopic Nikolsky sign can increase the sensitivity of histologic diagnosis of PV.