The aim of this review is to discuss those proteins for which the known 3D structure may be relevant to drug design. The majority of available information to date is from protein x-ray crystallography, though a growing number of studies are based on molecular modeling and NMR spectroscopy. The review concentrates on major progress reported in the literature from 1985 through the first half of 1991. Protein structures and related drug design studies have been loosely classified here into a number of major therapeutic areas: immunology, inflammation, cardiovascular disorders, cancer, viral and bacterial infection. Table I [GRAPHICS] lists those proteins discussed in this review for which 3D structural information is available.