In 1974, rapid cycling bipolar disorder has been defined by Dunner and Fieve as four or more episodes of depression or mania per year. Twenty year later, this definition appeared for the first line in an international classification of mental disorders in the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders. The rapid cycling phenomenon has been since studied with new adapted modified criteria taking into account different duration of affective episodes which characterise rapid cycling. Rapid cycling is associated with a low prophylactic efficacy of lithium and often represents a difficult approach for the clinician. Clinical aspects, influence of antidepressants associated with acceleration of cycles and possible therapeutic trials including non pharmaceutical treatment are discussed.