A review. Ab initio mol. dynamics (MD) allows realistic simulations to be performed without adjustable parameters. In recent years, the technique has been used on an increasing no. of applications to biochem. systems. Here we describe the principles on which ab initio MD is based. We focus on the most popular implementation, based on d. functional theory and plane wave basis set. By a survey of recent applications, we show that despite the current limitations of size and time scale, ab initio MD (and hybrid ab initio MD/MM approaches) can play an important role for the modeling of biol. systems. Finally, we provide a perspective for the advancement of methodol. approaches which may further expand the scope of ab initio MD in biomol. modeling. [on SciFinder (R)]