An attempt has been made to quantify the relative abundance and size distribution of oily-droplets in the ambient air of Shillong using an optical microscope. The sampling was carried out at controlled, moderate traffic, high traffic, traffic intersections, industrial estates and elevated specific locations in different seasons during 1998-2000. It was observed that the intensity of traffic and topography do not affect the relative abundance of oily droplets as % of total suspended particulates (TSP). Release of terpenes and/or other oily chemicals from pine-trees and other vegetation appeared to be a major source of oily-droplets in the ambient air with the abundance of oily-droplets reaching up to 15-25% of the suspended particulates by number in close vicinity of such forests/vegetation growths.