Scattered pockets of natural hill Sal forest in the southern foothills of Bhutan are the only remnant forests important for protection and conservation in southernmost Bhutan. The ecological study of Sal forest in Gomtu is the first of its kind in Bhutan and is aimed at enhancing future management and conservation programmes. We wanted to understand the floristic composition, diversity, and structural traits of this forest type in detail. A total of nine plots were sampled along the altitudinal gradients; trees and epiphytic vegetation were enumerated in all the plots. A total of 91 tree species belonging to 38 families were recorded (51 trees, 30 shrubs, 7 woody climbers and 3 palm species). Floristically, two major life-forms were exhibited; deciduous forest in the upper elevations mainly dominated by Shorea robusta and evergreen broad-leaved forest at the lower elevations. The entire study area was demarcated into three different forest types using cluster analysis; a Shorea dominant one on the ridge top, a Schima dominant one with Shorea at the lower altitudes, and a riparian one at the lowest altitude. The Shorea dominated type showed relatively low diversity and species richness compared to the other two types. The total basal area of Shorea robusta was 86,786.5 cm 2 /3,200 m 2 while the stem density was 123 stem/3,200 m 2 . The basal area increased from 2,146.2 cm 2 /400 m 2 to 18,926.0 cm 2 /400 m 2 while stem density increased from 3 stems/400 m 2 to 32 stems/400 m 2 with increasing altitude. However, the maximum estimated tree height decreased from 41.3 to 22.4 m approaching ridge tops. The study provided clear evidence that the most suitable range for the hill Sal forest was from a high altitude of 600 metre above sea level down to 527 m on northwest-facing ridge slopes.