Аннотация:First of all, the review gives a brief summary of the history of the discovery of this subclass of compounds. Natural sources of indolo[2,3-a]carbazoles, from bacteria and yeast to marine invertebrates, are described, and the corresponding compounds are listed. In addition, the review highlights the main approaches used to access synthetic representatives of this subclass, and the most promising of them are mentioned. A spectrum of biological properties of natural and synthetic indolo[2,3-a]carbazoles is described. Since the review focuses on the antitumor activity of this subclass of compounds, one of the sections is devoted to the description of the molecular mechanisms of the antitumor effect of indolo[2,3-a]carbazoles. Finally, examples of indolo[2,3-a]carbazole derivatives which are in clinical trials phase or are already used in the treatment of malignant neoplasms are given.