Atomic force microscopy is being used ever more widely in biological imaging, because of its unique ability to provide structural information at the single molecule level and under near-physiological conditions. Detailed topographic images of potential drug targets, such as proteins and DNA, have been produced, and the folding of modular proteins has been studied using single-molecule force spectroscopy. Recently, atomic force microscopy has been used to examine ligand-protein and ligand-DNA interactions, and to begin to determine the architecture of multi-subunit proteins, including a member of the superfamily of ionotropic receptors. Atomic force microscopy is fast becoming a valuable addition to the pharmaceutical industry's toolkit.