Boerhaavia species have been of keen interest in phytochemical and pharmacological research due to their excellent medicinal values. They are rich sources of alkaloids, steroids and flavones. Boerhaavia diffusa Linn. (Punarnava) has attracted a lot of attention due to its prevalent uses in Ayurvedic system of medicine. It is widely used in jaundice, hepatitis, oedema, oligurea, anemia, inflammation, eye diseases etc. Pharmacologists and clinicians have investigated B. diffusa for all these activities. In some cases the findings support the existing clinical uses. It possesses hepatoprotective, diuretic, anti-inflammatory, anti-stress and immunomodulation, antifertility, antimicrobial, antiviral and insecticidal activities. In conclusion, B. diffusa Linn. contains biologically active compounds that may serve as candidates for new drugs in the treatment and prevention of human and livestock diseases.