The first closures are scheduled to take place in July
Post offices on the Western Isles, Shetland and Orkney will be closed following public consultation.
Sixteen branches will shut with the first closures scheduled to take place in July, Post Office Limited said.
They are Gress, Grimshader, Knock, Leurbost, Borve, Breasclete, Shader, Sidinish, South Dell and Tigharry on the Western Isles.
Burray, Harray, Rendall and Swannay on Orkney, and Camb and Levenwick on Shetland, will also close.
The future of Western Isles branches at Bragar, Skigersta and Northton are now being reviewed.
Western Isles SNP MP Angus MacNeil said he was disappointed at the closure of 10 isles branches and hoped the three under review would remain open.
Scottish Lib Dem Orkney and Shetland MP Alistair Carmichael accused the Post Office of neglecting residents.