Given its 60-year history, it might be tempting to see similarities in physical appearance of the originally marketed pressurised metered dose inhaler (pMDI) with its present form and conclude that little has changed during its lifetime. This however would be specious, since significant advancements have been made in all aspects of the pMDI, including hardware, formulation and performance. The pMDI remains the most widely used inhaler device worldwide for a variety of reasons. Clearly the introduction of the Montreal Protocol with the switch from CFC to ozone-friendly HFA propellants stimulated new research into the fundamental aspects of particle science, device technology and aerosol generation. This has resulted in new strategies to modulate the performance and broaden the applicability of pMDIs. The use of: engineered particles; solubilisation aids including cyclodextrins, and nanoparticles; suspension stabilisers including porous phospholipid particles; lactose and amino acid carrier systems; have all been applied to optimise lung delivery and extend the scope of pMDIs to a wider range of drugs, drug combinations and doses. In addition to small molecule applications, strategies are evolving to formulate macromolecules and biologics, including proteins, DNA, vaccines and bacteriophages. The potential evolution of new propellants with even lower environmental impact will offer future challenges but the wealth of research conducted over the past two decades will help overcome the task ahead. One key driver for the continued development of the pMDI is its global appeal to a broad spectrum of patients.