Medicine Lake Volcano, Shield volcano in Siskiyou County, United States.

Medicine Lake Volcano is a shield volcano in northeastern California whose broad flat crater encloses a lake at around 7900 feet (2400 meters) elevation. Built from basalt, the mountain extends over a wide area with lava fields and pine forests spreading gently outward.

Medicine Lake Volcano began to grow about one million years ago in Pleistocene time, after a large eruption of tholeiitic high-alumina basalt. Its growth is divided into five stages, from early silica-rich volcanism through caldera-rim construction to large basalt flows. The most recent eruption, around 1,000 years ago, produced rhyolite and dacite at Glass Mountain near the caldera's eastern rim.

The volcano and its lake lie within the Sáttítla Highlands, named a national monument in 2025 by President Joe Biden to protect the area from development. The surrounding highlands are largely managed by the United States Forest Service as part of the Klamath, Shasta–Trinity and Modoc National Forests.

The caldera and Medicine Lake lie at the end of a forest road off California State Route 89, about 30 mi (50 km) northeast of Mount Shasta. The highlands are largely managed by the United States Forest Service within Klamath, Shasta–Trinity and Modoc National Forests. Lava Beds National Monument sits on the northeast flank of the volcano.

The shield's lava flows total at least 140 cubic miles (600 km³), the largest volume of any Cascade Range volcano, ahead of Newberry Volcano in Oregon. The summit is Mount Hoffman, given as 2,414 m in some sources and 2,376 m in others. The caldera measures 4 by 7 miles (7 by 12 km).