Ozonized sunflower oil Topical OLEOZON is used as an antimicrobial product. It has been approved its Medical Registry for Epidermofitosis and Impetigo diseases, pathologies of fungicide and bactericide origin very frequent in many countries. Generally, is known that fragile and breakable nails are result of normal ageing. However, several diseases and harmful local products can damage the nails. In the present study, the effect of Topical OLEOZON in the treatment of fragile and breakable nails was demonstrated in a controlled clinic assay, in 50 patients that assisted to Dermatology service at Salvador Allende Hospital. The treatment administered was twice per day for a period of 6 month. The efficacy was evaluated clinically by visual test and the patients with flexible and tough nails were considered cured. On the other hand, the patients with more than 50 % of flexible and tough nails were considered improved. A complete clinical cure was obtained in 72% of patients that finish this study. The other patients were improved for 28 %. No side-effects were observed. Topical OLEOZON can be an effective alternative low-cost in fragile and breakable nails treatment. This product has been approved for Health Cuban Authorities as nails toughener.