Passenger numbers at Inverness Airport slid by 6.7% to 61,347 in July, new figures show.
Operator Highlands and Islands Airports (Hial) said the year-on-year drop was due to the loss of flights to Zurich and fewer charter services.
Hial reported a 3.4% fall in traveller numbers across its 11 airports last month, to 134,463.
The biggest drop was at Dundee, down 23.5% to 2,437, while Wick suffered a fall of 21.1% to 3,582.
An 8% slump in the number of people using the terminal at Kirkwall, to 17,550, also contributed to the overall dip.
By contrast, the airports on Barra, Tiree and Benbecula enjoyed increases of 24.7% to 1,453, 15.9% to 1,308 and 15.1% to 3,370 respectively.
Campbeltown’s terminal was used by 1,055 passengers, a 22% increase and Islay was up by 1.7% at 2,616.
Sumburgh and Stornoway airports grew their passenger figures by 5% to 27,606 and 4.3% to 12,139 respectively.
Hial managing director Inglis Lyon said: “There was continued growth across many of our island airports.
“Sumburgh remains particularly buoyant, given the sustained growth in energy traffic.”
Mr Lyon said new services to London City and Dublin, extra flights to Manchester and the return of Geneva to the destination roster should usher in a period of growth at Inverness.