Over the last 20 years, inhalation drug delivery has been adjusting to the phase out of chlorofluorocarbon (CFC) propellants. Following the signature of the Montreal Protocol on September 16, 1987, there has been a rush to re-formulate pressure metered dose inhalers (pMDIs) using alternative propellant systems. This has led to the advent of dry powder inhalers (DPIs), and to a prolific HFA (hydrofluoroalkane) pMDI patent field, resulting in a crowded patent landscape. The complexity of this landscape has led to myth and confusion with respect to the risks and opportunities in formulating HFA pMDIs. This review aims to improve understanding of the intellectual property (IP) landscape. Understanding the past could help industry participants plan the future of pMDI inhalation delivery.