To date, literature reports various cases of nail injury associated with gel-manicure, including contact-allergic reactions, periungual eczematous dermatitis, acute onychodystrophy with psoriatic changes in nail plates, onycholysis, and subungual hyperkeratosis. The article presents medical aspects of the use of materials containing acrylate and methacrylates, as well as mechanical effects during nail service procedures. The importance of differential diagnostics of nail lesions induced by methacrylates and similarity of clinical symptoms of these conditions with onychodystrophies resulting from other causes and common diseases have been substantiated. Five clinical cases of nail injuries resulting from manicure using gel-lacquer were reported. The data obtained during examination, dermatoscopy, and microscopic examination of scraping from the nail plates of patients were used. The reported cases should contribute to increased alertness during careful history taking in terms of application of gel-lacquer in patients with onychodystrophy and, especially, in the cases of nail psoriasis. We provided recommendations to patients on the required preventive measures before and after nail treatment aimed at reducing the risk of nail injury associated with manicure or pedicure using gel-lacquer.