Prevalence of the onychomycosis increases every year. To optimize treatment the pathogens have to be identified. Mycological examination is currently a gold standard for the diagnosis but other diagnostic tools e.g. molecular genetic techniques are developed. Also many modifications of the standard diagnostic examination, which improve its sensitivity and specificity, are present. In the treatment three main strategies are present now: topical, oral and combination. The new regimens of oral and topical treatment are proposed and new antifungals which were recently developed broaden the treatment possibilities. Despite many protocols, the current treatment rate is still disappointing, and many reasons of the failure are considered. The main one is probably poor penetration of the drug into the affected nail. Pharmacokinetic researches proved that concentrations of the medicine in a healthy nail plate are much higher than in the lesional one. Also relapses and reinfections remain stubborn problems in the management of the onychomycosis.