Data on the chemistry of azafluorenes (indenopyridines) for the last two decades are summarised. Methods of synthesis of all isomeric (as regards the position of the nitrogen atom) azafluorenes are considered. The main reactions of azafluorenes are analysed, their reactivity is determined by the presence and mutual influence of two different conjugated fused rings (benzene and pyridine) and the mode of fusion of the indene and pyridine fragments. The principal conversions of substituants at different positions of the azafluorcne system are considered. Evidence is presented on the natural occurrence of azafluorenes, the biological activity of their synthetic derivatives, and on the structure and physicochemical properties of azafluorenes and their derivatives. © 1997 Russian Academy of Sciences and Turpion Ltd.