A mask fitting system (1) for selecting a mask system for a patient includes at least one terminal (6) which receives data unique to a patient. The patient data can be scanned in using a scanner, such as a handheld or 3-D scanner, or the relevant dimensions of the patient can be simply input into the terminal. A database (2) is provided to store mask system data relating to a plurality of potential mask system solutions for the patient. A communication channel (4) is provided by which the data received by the terminal can be compared with mask system data stored in a mask system database, so as to generate a best-fit mask system result. The best-fit result may include one or more mask system recommendations for the patient.