Manitoba Tall Grass Prairie Preserve, Nature reserve in southeastern Manitoba, Canada.

The Manitoba Tall Grass Prairie Preserve is a nature reserve near Gardenton and Vita in southeastern Manitoba, about 50 kilometres south of Steinbach. It protects a mosaic of tallgrass prairie, aspen woodland, sedge meadow wetland, riparian woodland and oak savannah, with over 5,800 hectares protected as of 2025.

Botanists of the Manitoba Naturalist Society cataloguing native plants in the late 1980s found that a large part of the tallgrass prairie had survived, contrary to the belief that it was gone. Protection followed, and by 2025 over 5,800 hectares were protected. Much of the land escaped ploughing because glacial boulders made it unfarmable by machine.

The preserve's name comes from the tall grasses that once covered the region. Each August, Gardenton hosts Prairie Day on the second Saturday, when residents show the preserve's flora and fauna and teach children about species such as the smooth green snake. The 13-part series Canada: A People's History was filmed here for its First Nations encampments and Metis ox carts.

The Nature Conservancy of Canada maintains the 1.6 km Agassiz Trail in the Vita area and the Prairie Orchid Trail beside the Weston Family Tall Grass Prairie Interpretive Centre in Stuartburn. A separate 1.5 km trail, laid out in the southern part of the preserve, is owned by the Manitoba Habitat Heritage Corporation, a provincial Crown corporation that holds land near Vita.

The western prairie fringed orchid (Platanthera praeclara) here forms the world's largest population of the species, holding over half of all known plants; it is the last remaining Canadian stand. The small white lady's slipper is also present: 34,491 stems were counted in 1998, 16,899 of them flowering.