Background: Onychomycosis is the most common disease of the nails., Objective: This retrospective study aimed at evaluating the epidemiology of onychomycosis in adult patients in South Greece during the 2015-2017 period., Material and Methods: A total of 3,226 patients with clinical signs of possible onychomycosis were included. Diagnosis was confirmed by microscopy with KOH 20% and by culture in Sabouraud agar with and without actidione., Results: Diagnosis of onychomycosis was confirmed in 27.99% of the patients. Men were infected more often (40.04%) than women (23.30%). Toenails (68.77%) were infected more than fingernails (31.23%) in both sexes. Onychomycosis in fingernails was more common among women (39.74%) than men (18.51%). Men were more often diagnosed with onychomycosis in toenails (81.49%) than women (60.26%). Dermatophytes were the most frequently isolated fungi (34.11%), followed by Candida (29.79%) and non-dermatophyte molds (NDM) (7.20%). In fingernails, the most frequently isolated fungus was Candida spp. (84.04%), followed by dermatophytes (3.55%) and NDM (0.71%). In toenails, dermatophytes (47.99%) were more commonly identified, followed by NDM (10.14%) and Candida spp. (5.15%)., Conclusion: Onychomycosis in Greece follows a pattern of higher incidence in males, with toenails more frequently infected with T. rubrum and fingernails more frequently infected with C. albicans in the present era., Competing Interests: None declared by all authors., (Copyright © 2019 by S. Karger AG, Basel.)