An increasing number of newly developed drugs are poorly soluble; in many cases drugs are poorly soluble in both aqueous and organic media excluding the traditional approaches of overcoming such solubility factors and resulting in bioavailability problems. An alternative and promising approach is the production of drug nanoparticles (i.e. nanosuspensions) to overcome these problems. The major advantages of this technology are its general applicability to most drugs and its simplicity. In this article, the production of nanoparticles on a laboratory scale is presented, special features such as increased saturation solubility and dissolution velocity are discussed, and special applications are highlighted, for example, mucoadhesive nanosuspensions for oral delivery and surface-modified drug nanoparticles for site-specific delivery to the brain. The possibilities of large scale production -- the prerequisite for the introduction of a delivery system to the market -- are also discussed.