Drones are being used to carry Covid-19 samples and test kits in some parts of Argyll and Bute - in what has been described as a UK first.
Following a trial last year, the project has been expanded, with medical cargo now being carried up to 40 miles (64km).
Flights from Mull, Clachan-Seil and Lochgilphead to Lorn and the Islands Hospital in Oban have been authorised.
NHS staff will be able to request drone deliveries.
The drones can carry a payload of up to 3kg (6.6lbs) and cover distances faster than they can be by road. Some of the road journeys also involve a ferry crossing.
Drone operator Skyports has been given permission by the Civil Aviation Authority for the flights.
Skyports said deliveries - which are being done for the Argyll and Bute Health & Social Care Partnership - were the first of their kind in the UK.
The service will initially operate between Lorn and Islands Hospital in Oban, Mid-Argyll Community Hospital in Lochgilphead, Easdale Medical Practice in Clachan Seil and the Mull and Iona Community Hospital in Craignure.
Both a scheduled service and an on-demand service will be run, with orders able to be placed by NHS staff through an online system developed by digital consultants Deloitte.
The Swoop Aero drones will be controlled from an operations centre in Oban and fly automatically along predefined routes.
Skyports said communication between the drone and the ground control station will be provided by Vodafone's 4G network and satellite communications to ensure connectivity coverage is provided at all times.
The project has been funded by a joint initiative between the UK Space Agency and the European Space Agency.
Stephen Whiston, head of strategic planning for Argyll and Bute Health and Social Care Partnership, said the aim of the project was to improve services for patients and clinicians in "some of our most remote and island communities".
He added: "This three-month project working with Skyports will provide critical evidence on the real benefits this technology can bring to the NHS not only in Argyll and Bute but across Scotland."
Skyports chief executive Duncan Walker said: "Using drone deliveries within supply chains can create significant time and cost savings.
"This initiative is a natural progression from our recent trials with the NHS in Scotland as we scale our operations, supporting a wider network of hospitals and medical practices as they continue to respond to the Covid-19 pandemic."
Mr Walker said it was hoped the initiative would bring permanent drone medical flights a step closer.