Background: Plica as a disease entity appeared fi rst in the 13th century. Its aetiology is still unknown and not fully understood. Being, in fact, an irreversible condition of tangling and felting the hair, its origin was interpreted in various ways, from religious ones, through lack of hygiene to mental illness. Although p. polonica originates from Eastern and Central Europe, and p. neuropathica, typical of Indian people, was fi rst described in England, many characteristics connect these two conditions. Aim and Objectives: The study aimed to review the plica species over the centuries and to compare p. neuropathica and p. polonica. Materials and Methods: PubMed and Google Scholar databases were searched for medical articles, books and case studies on plica published up 1884 to 2020. We conducted a systematic and critical review of the literature to compare p. polonica and p. neuropathica. Results: Plica polonica and Plica neuropathica are the same disease entity. Conclusion: The variety of names and interpretations of the disease has made plica a condition still to be fully explained.