Boerhaavia diffusa is a plant which is extensively used in folk medicine. However, when it comes to its phytochemical characterization, little attention has been given to secondary metabolites other than rotenoids and alkaloids. A metabolite profiling and biological study was undertaken in this species' leaves and roots and substantial differences were found between the two parts of the plant. The volatile composition was analysed for the first time using HS-SPME-GC-MS and several compounds, including terpenes, phenylpropanoids, indol compounds, norisoprenoids, among others, were identified. Organic acid analysis was also performed, allowing their characterization in this species for the first time, and oxalic, ketoglutaric, pyruvic, quinic and fumaric acids were identified. Quantitative differences between the two vegetal materials were found. Additionally, several flavonoids and one phenolic acid were also confirmed. Concerning the biological potential, the aqueous extract of each plant part was tested against DPPH radical, one reactive oxygen species (O(2)(-)) and one reactive nitrogen species (()NO). Moreover, activity against acetylcholinesterase, an enzyme with a well-known role in several physio-pathological processes, was assayed. When possible, the relation between the chemistry and activity displayed was established. Leaves revealed stronger antioxidant activity than roots, and acetylcholinesterase inhibition was not found in neither plant part.