Bipolar disorder with a rapid cycling course can be difficult to treat, often involving therapy resistance. A 55-year old patient with bipolar disorder with rapid cycling course did not stabilize for years, despite various pharmacotherapeutic treatments. Only after lithium was introduced as a maintenance treatment at a level of around 1.20 mmol/l, a long-term stabilization of mood developed which also persisted. A literature review was performed which concluded that maintenance treatment with lithium at levels above 1.0 mmol/l in patients with rapid cycling bipolar disorder has not been adequately studied.