NHS SHETLAND medical director Gilbert Ozuzu is set to leave his post at the end of September.
Dental director Brian Chittick will take on the role on an interim basis while continuing his existing post.
Ozuzu, who was appointed in June last year, is leaving Shetland to be closer to family in England.
NHS Shetland chief executive Ralph Roberts said: "We would like to thank Dr Chittick for taking on this role and I look forward to working with him and colleagues to ensure that NHS Shetland has effective clinical leadership and engagement.
"Dr Chittick has been dental director for a number of years and, under his leadership, the dental service has developed while addressing many historic challenges."
Assistant medical director for primary care Dylan Murphy will assist Chittick, as will senior consultants at the Gilbert Bain Hospital in Lerwick with expertise in their own clinical services.
Chittick, a former Royal Naval officer and forensic odontologist, added: "Gilbert has laid a solid foundation and I am confident we can continue with the projects and improvements that he has set in motion. I would like to send him best wishes for the future."
Recruitment to the medical director post will start in due course.