Interest in applications of protein crystallography to medicine was evident as the first high-resolution structures emerged in the 50s and 60s. In Cambridge Max Perutz and John Kendrew sought to understand mutations in sickle cell and other genetic diseases related to haemoglobin, while in Oxford the group of Dorothy Hodgkin became interested in long-lasting zinc-insulin crystals for treatment of diabetes and later considered insulin redesign as synthetic insulins became possible. The use of protein crystallography in structure-guided drug discovery emerged as enzyme structures allowed the identification of potential inhibitor-binding sites and optimisation of interactions of hits using the structure of the target protein. Early examples of this approach were the use of the structure of renin to design anti-hypertensives and the structure of HIV protease in design of AIDS antivirals. More recently, use of structure-guided design with fragment-based drug discovery, which reduces the size of screening libraries by decreasing complexity, has improved ligand efficiency in drug design and has been used to progress three oncology drugs through clinical trials to FDA approval. We exemplify current developments in structure-guided target identification and fragment-based lead discovery with efforts to develop new antimicrobials for mycobacterial infections.