Background: At present time, the diagnosis of onychomycosis is based on clinical signs, direct exam and fungal culture, whereas Pathologic methods have shown to be more sensitive than other methods. Objective: Evaluation of pathologic methods in the diagnosis of onychomycosis in comparison to direct smear and culture. Patients and Methods: A nail sample was cut form 96 suspected onychomycosis patients by nail clipper. Then it was divided to four pats, and one part was stored. One part was fixed in 4% formalin and examined pathologically (PATH-PAS method). Another part was cultured in mycosil agar and Sabour and Dextrose Agar media and kept in room temperature for 4 weeks. Another part was directly examined by 10% KOH. The results of each method were recorded separately without knowing the results of others. Clinical signs with at least one positive result were considered as onychomycosis and the sensitivity of these methods were compared. Results: The most sensitive method was the combination of PATH-PAS and direct smear (98%). There was no significant difference between the sensitivity of smear and pathological method, where as PATH-PAS and culture differed significantly. Conclusion: PATH-PAS is a simple and very sensitive method in the diagnosis of onychomycosis.