(1) The effect of fire on growth and allocation of biomass and nutrients in Mikania micrantha, an early successional exotic weed, was studied in seral communities developed after slash-and-burn agriculture (jhum) in north-eastern India. (2) In successional fallows, plant vigour was stable in burnt plots, but declined with age in unburnt plots. Biomass and nutrient allocation to seeds was higher in burnt than unburnt 8-year old plots. (3) Nutrient uptake efficiency was higher after burning and increased with age, but decreased with age in unburnt fallows, probably reflecting differences in soil nutrient availability and competition. (4) Nutrient-use efficiency was inversely related to uptake efficiency and may be a compensatory mechanism for survival. (5) It is concluded that M. micrantha is adapted to survival after fire.