Probiotics are live microorganisms, which when administered in adequate amounts confer a health benefit on the host - so is the definition of probiotics according to the recommendations of World Health Organization (WHO) and Food and Agriculture Organization of the United Nations (FAO) also supported in Poland by the Polish Society for Probiotics and Prebiotics. In an analysis of the literature over the last years one can tell that safety of probiotics is as important as the benefits coming from their use. In FAO/WHO recommendations we can already find information about their safety. This article describes the problem of probiotics’ safety in the context of potential risk of clinical complications after ingestion.