Background: Keeping short, unpainted nails is a significant element of effective hand disinfection among nurses. The aim of the study was to examine the qualitative microbiological purity of painted nails after hand disinfection, taking into account the type of the nail varnish. Material and Methods: Materials were collected from 188 nurses. The results were compiled according to the type of the nail varnish applied on the nail plate. The control group consisted of 24 nurses with natural nails. An indicator of the effectiveness of hand disinfection was the number and type of bacteria grown from the materials collected from the participants’ hands – from the nail plate, from under the nail plate and from the skin around the nail plate. Results: In the case of the nail plate swab method, the highest percentage of pathogenic microorganisms grew on the nails covered with a regular varnish (21.7%, p < 0.05). A long-lasting (10 days on average) regular nail varnish was likely to result in ineffective hand disinfection (p < 0.001). In the test involving dipping the finger in tryptic soy broth combined with the technique of collecting swabs from under the nail plate, the highest percentage of pathogenic microorganisms was grown from the nail plate coated/extended with gel and then painted with a 14.8% hybrid varnish (p < 0.05). Conclusions: The risk of growing a pathogenic microorganism after hand disinfection due to nails coated with a conditioner or a hybrid varnish was similar to that of natural nails. A long-lasting regular nail varnish increases the risk of ineffective hand disinfection. Modeling and/or extending the nail plate with a LED/UV light curing gel, and then painting it with a hybrid varnish, also increases the risk of ineffective hand disinfection. Med Pr. 2021;72(1):29–37