Synopsis There exists an estimated number of approximately 650 species of bees (Apoides, Hymenoptera, Insecta) which are widely distributed within territories of Indian region. Grouped under 10 families, they vigorously pollinate around 3,000 species of Angiosperms. Family Megachilidae constitutes about 40% alone of the bee fauna of this country. This research publication describes 166 species of Megachilidae collected from 110 locations of north-western India. Grouped within 36 subgenera and 26 genera, each species description is followed by their complete collection data and flower record. The taxonomic publication supported by all level identification keys and detailed figures, is first of its kind since the work of Fauna of British India (1897) for the family. The author, working on non-Apis bee taxonomy since 1979, has recategorised all species as per the recentmost taxonomic framework of the family. The publications is significantly of fundamental value and great use to the taxonomists, see biologists and workers of pollination biology throughout the world.