The Strathclyde Gay and Lesbian Switchboard (SGLS) which was set up on Union Street, Glasgow, in 1977, will shut on Scotland’s Hogmanay (New Years Day).
The charity said its major contributor, NHS Greater Glasgow and Clyde, cut funding two years ago leaving SGLS surviving on savings since.
Another health board recently also scrapped its funding.
The service provides information, advice, arranges support meetings and one-to-one communication for the region's LGBT community.