This article presents information on paraneoplastic syndromes (PNS) — various pathologies and conditions that accompany and sometimes precede the onset of malignant visceral neoplasms. Although some of the PNS and neoplastic processes are not always equal, detection of PNS is an important marker associated with formation or progression of cancer. PNS definitions are still being under lively discussion in research community. Risk of PNS onset doesn’t depend on patient’s nationality, age and gender. A brief clinical description of PNS, which are mostly widespread in general therapeutic practice, is given: general, rheumatological, renal, hematological, endocrine, neurological, gastrointestinal and dermatological. Bu to date, more than 60 PNS have been described, and their list continues to grow. There is no single generally accepted PNS classification. It is proposed to classify PNS depending on the leading pathogenetic mechanism, degree of connection with malignant visceral neoplasm, dominant clinical manifestation. Concept of «dermatological PNS» is outlined according to Helen Kurt’s postulates. Manifestations of «typical» dermatological PNS in gastroenterological pathology are described. Skin changes in hereditary PNS are described (Cowden, Peitz–Jägers, Gardner syndromes), as well as dermatological manifestations of hormone-secreting tumors (ACTH-ectopic, carcinoid, glucagonoma syndromes) are characterized. Attention is paid to the pathogenesis and diagnosis of hereditary PNS, hormone-secreting tumors, their diversity and manifestation features.