Structure-based drug design, a terminology used to describe rational drug design by complementing the structure, spatially and chemically, of the target macromolecule, is rapidly developing as one of the innovative approaches to drug discovery. A growing volume of protein structure data and new techniques of protein structure determination make this all possible. The method of structure-based drug design and a specific example of the design of influenza virus neuraminidase is briefly presented. A whole new class of influenza virus neuraminidase inhibitors has been designed that can potentially be developed as antiinfluenza drugs.