Synopsis The present work is the outcome of a series of ethnobotanical field surveys conducted in Kumaon and Garhwal Himalayas of the western Uttar Pradesh, for about a decade since 1983. It enlists 691 medicinal plants species arranged in alphabetical order providing information on their botanical name, family, varnacular name(s), locality and collection number, habit and habitat, therapeutic action and uses, ethnomedicinal field data, biodynamic notes (comprising bioactive constituents and pharmacological effects). Of these 536 are medicinal and 154 seem to be still documented for their medicinal potential. The study indicates that over 127 taxa of plants find wide use in local therapy for various diseases and conditions. These have been discussed in detail providing folk-prescriptions and mode of application in each case. Besides, many medicinal species facing threat to their survival and depleting fast in this region due to various factors have been highlighted and strategies for their protection and conservation suggested. This is the most up-to-date contribution on the herbal drugs of this important hilly tract of western Himalayas in India and aimed at a wide audience of ethnobotanists, phytochemists, pharmacologists, pharmacists and other research scientists engaged in the search of new drugs from natural resources.