Physician assistants (PAs) have medical training and work supervised by a doctor. In 2006-2008 the Scottish Government piloted use of USA-trained PAs. The aim of the paper is to evaluate the impact and contribution made by PAs to delivering effective health care in National Health Service (NHS) Scotland. Mixed methods, longitudinally, including interviews, feedback forms and activity data collection. Data analysis used nVivo, SPSS and Excel. Participants were 15 USA-trained PAs, medical supervisors and team members, 20 patients, four NHS senior managers and three trade union representatives. Settings were four Scottish NHS Boards where PAs worked in primary care, out of hours clinics, emergency medicine, intermediate care and orthopaedics. Two minor patient safety issues arose. Patients were satisfied with PAs. Scope of practice did not replicate US working. Inability to prescribe was a hindrance. PAs tended to have longer consultations, but provided continuity and an educational resource. They were assessed to be mid-level practitioners approximating to nurse practitioner or generalist doctor. Valued features were generalism, medical background, confidence differential diagnosis and communication. Interviewees suggested PAs could fulfil roles currently filled by medical staff, potentially saving resources. In conclusion, there is potential for PAs to fulfil distinctive mid-level roles in the Scottish NHS adding value in continuity, communication and medical approach.