Onychomycosis is a fungal infection of the fingernails and/ or toenails caused by dermatophytes, yeasts and non-dermatophyte moulds. The epidemiology of onychomycosis in Serbia is yet to be fully established. This epidemiological study was aimed at evaluating the epidemiology of onychomycosis in a sample of the Serbian patients at risk of onychomycosis, to determine the fungal aetiological agents and to identify the possible risk factors. The study population included 374 patients from six centres in Serbia with suspected onychomycosis. Demographic data, data about comorbidities, lifestyle, clinical aspects of onychomycosis, trauma, excessive perspiration and personal and family history of previous onychomycosis were studied. Laboratory confirmation of diagnosis was done by direct microscopy, fungal culture and PCR. Diagnosis of onychomycosis was confirmed in 50.8% of patients, who tested positive to at least one laboratory test (direct microscopy, fungal culture or PCR). Trichophyton rubrum was predominant both on toenails (85.98%) and on fingernails (38.46%). Independent risk factors for onychomycosis were: old age (OR = 2.285; P < 0.001), family history of previous onychomycosis and/ or tinea pedis (OR = 2.452; P = 0.005), excessive perspiration (OR = 2.165; P = 0.002) and higher degree of hyperkeratosis (OR = 1.755; P = 0.020). This is a first epidemiological study of onychomycosis from Serbia.