We describe a case of tinea unguis in a 20 year old female student from Caracas. The peri-ungual skin of a thumb appeared altered first and, since 6 months, the lamina was being progressively invaded and destroyed. At the direct mycologic examination numerous, regular and irregular, hyaline fungal hyphae were visible. Culture was performed 9 times: several molds did grow, among which, eight times, we got numerous colonies of a strain that has been identified to Nannizzia gypsea (+). Owing to the rarity of the observation the bases for the diagnosis are discussed and the pertinent literature is reviewed.