The family Acanthaceae has been studied and revised taxonomically for the State of Kerala. The study reveals that there are 33 genera, 147 species and 4 varieties in the present political boundaries of Kerala. Important literature of Acanthaceae pertaining to India in general and particularly to Kerala has been briefly reviewed. The varied habitats, habits and the macro and micro-morphological characters and distinguishing characters of the taxa have been described in detail. Dichotomous keys to the genera, species and varieties are provided. For each species nomenclatural citation with relevant synonyms, descriptions, data on phenology, distribution, status, vernacular names, ethnobotanical data, specimens studied and notes, wherever necessary are provided.