Mallotus nudiflorus (L.) Kulju & Welzen is a medium sized deciduous tree under the family Euphorbiaceae with Nativity from the Himalaya to Hainan Island. In India it is distribution throughout the hotter parts, moist semi-evergreen tropical forests along river and water courses. The plant is traditionally used in Indian Ayurvedic medicine. Lipid classes and fatty acid compositions of seed oil considered a cheap raw material in surface coating industry. The present study investigated the variation of fatty oil content of M. nudiflora from populations of different agro climatic zone of Assam. Five Agro climatic zone of Assam were selected, extensive field surveys were done for authentication of extent of population and distribution maps were prepared accordingly. Twenty (20) populations were studied; fruits were de pulped and pale yellow coloured oil was extracted with Soxhlet apparatus using hexane as solvent. The highest percentage of oil found in Bilasipara population (25.12±0.17%) of Lower Brahmaputra Valley Zone, and lowest in Kolajan of North Bank Zone (1.51±0.52%). Diversity in specific climato-ecological characteristics of agro climatic zones influenced the variation in oil content of studied populations. Present results facilitated a great opportunity intended for selection of superior population in favour of obtaining high fatty oil yield from seeds M. nudiflorus at commercial scale.