Andrographolide (AG) is a main effective ingredient in leaves of Andrographis paniculata. AG and its derivatives have such effects in anti-infection, anti-tumor and immuno-regulation. Particularly, its antibacterial, antiviral and anti-protozoal activities play an increasingly important role in resisting opportunistic infections. On the basis of our studies on AG over the years, we made a summary for the basis and clinical studies on AG and its derivatives over the past 10 years.