1) Fungal nail infection, or onychomycosis, mainly affects toenails. Infections are generally asymptomatic. Spontaneous regressions, but also complications, appear to be rare. Discomfort and cosmetic complaint are occasionally reported; 2) After a review of the literature based on the standard Prescrire procedure, we examined the diagnosis and management of fungal nail infections; 3) Clinical signs of fungal nail infections are non-specific. Alternative diagnoses include psoriasis and nail microtrauma. Nail hyperkeratosis and leukonychia are useful diagnostic pointers. Matrix involvement has important implications in the choice of treatment; 4) Detection of fungal structures by direct examination of a nail sample is strongly suggestive of fungal nail infection. In contrast, cases of negative direct examination with positive culture must be interpreted with caution, as contamination is frequent; 5) Antifungal lacquers (5% amorolfine and 8% ciclopirox) applied to the nails cure about 30% of fungal infections and sometimes cause mild irritation. There is no firm evidence that these solutions are any more effective than other topical antifungals applied daily to the affected nail. Trimming, filing or grinding the nail, in addition to these drug treatments, is likely to be beneficial, but these measures have not been evaluated; 6) Chemical nail destruction with a combination of urea and bifonazole, followed by treatment with an antifungal ointment, can be used when the nail is markedly thickened. Non-comparative trials have shown cure rates close to 70% at three months when the matrix is not involved, and 40% with matrix involvement. Drug application is inconvenient and local reactions are frequent. Surgical nail avulsion carries a risk of local infection and permanent nail dystrophy; 7) Oral terbinafine is effective in more than 50% of cases but its cutaneous, hepatic and haematological adverse effects are severe in about 1 in 2000 patients and can be life-threatening; 8) It is better to treat Candida nail infections with oral azoles (ketonazole, itraconazole) than with terbinafine. These treatments carry a risk of serious adverse effects and numerous drug interactions; 9) Fungal nail infections are usually mild. Treatments with potentially severe adverse effects must therefore be used with caution. It is better not to treat fungal nail infections if the risks outweigh the expected benefits.