Recent progress in spectroscopic, photophysical, photochemical and analytical studies, as well as in the biological and biomedical properties of bioactive phenothiazines and benzophenothiazines, is reviewed. Their electronic absorption and luminescence properties, and their complexation and interactions in organized media are discussed. Various applications, including analytical studies, relative to phenothiazines and benzophenothiazines are described. Among the important biological and biomedical properties of these compounds, their neurological effects, their antibacterial, antifungal, antiviral, antiparasitic and antitumour activities, and their cytotoxicity are particularly reviewed.