An apparatus and method are provided for selectively applying an agent-containing liquid coating to extremely tiny skin piercing microprojections (10). The coating solution is applied to the skin piercing microprojections (10) using a coating technique which selectively coats only the skin piercing microprojections (10) and not the substrate (12) from which the microprojections (10) extend, and then dried. The coating method includes providing an agent-containing coating liquid and conveying the liquid to a liquid holding surface having a coating transfer region. The depth of the coating liquid at the coating transfer region is precisely controlled. The microprojections are then immersed to a predetermined level in the coating liquid. The liquid that coats the microprojections (10) is then dried to form a solid agent-containing coating on the microprojections (10).