Fire causes effects on diverse aspects of plant functioning and development, many of them linked to survival. However, the response of native vegetation to this disturbance possibly reveals a plant strategy to tolerate fire linked to the biosynthesis of compounds like chlorophylls and secondary metabolites. The aim of this study was to evaluate whether fire severity could promote the biochemical tolerance to fire by influencing the biosynthesis of chemical compounds. To test this, we exposed six woody species from the Chaco region to an experimental burn of medium severity at fire season ending in the study area. In this burn, we established individual plots for each plant. Fire severity was estimated visually as the burnt biomass of each plant, which was considered as the percentage of the loss of aboveground biomass. Then, the biochemical plant response to fire was studied, through the changes in the concentration of photosynthetic pigments (chlorophyll and carotenoids), and secondary metabolites (phenolic compounds and tannins). The metabolites quantification was carried out by using spectrophotometric methods. As results, a strong correlation was found between the biosynthesis of metabolites in response to fire and the amount of burnt biomass during the experimental burns. This correlation could be considered as an indicator of the burnt plant response to stress. In our results, shrubby species showed both the higher amount of burnt biomass and the enhanced biosynthesis of compounds in the resprouts post-fire, which could be related to the capacity of these species to stablish in disturbed environments. Our study provides an insight into the understanding of the plant strategies to fire tolerance and resilience in natural environments.