The Orion medical frigate was a type of medical ship employed by the Orions in the 21st century. Such vessels were used to cure the Great Plague.
The frigate was equipped with advanced ventilation systems for cleaning the air, and regenerative auxiliary power systems that could stay operational even after hundreds of years.
In 2382, Mistress D'Erika Tendi acquired the coordinates for a derelict Orion medical frigate on Alva IV from a rogue archaeologist. Believing it to be a warship, she sent her sister D'Vana to secure it, which would represent a huge symbolic victory for their House. She assured D'Vana that doing so would pay off the remainder of her debt, allowing her to return to Starfleet.
Arriving at the wreck, D'Vana's party ran afoul of another party from House Azure, who had also bought the coordinates from the archaeologist. To defeat them without killing them, D'Vana flooded the frigate with laughing gas. She then flew the ship back to the Tendi family home on Orion. (LD: "Dos Cerritos")