background: bipolar disorder is a highly recurrent severe psychiatric disorder. the number of episodes has been found consistently associated with poor outcome. it has been suggested that bipolar patients with long duration of illness and highly recurrent course show great impairment of global functioning. objectives the aim of this study is to assess the clinical course and outcome of patients with bipolar disorder i and ii with a high number of mood episodes. methods: we compared a group of bipolar i and ii subjects whose number of episode was higher than ten (n = 167) with a similar-size representative sample of bipolar patients whose number of episodes was lower or equal than ten (n = 131). results: bipolar patients with more than 10 episodes have a more severe outcome of bipolar disorder. qualification and occupational status was clearly worse for the highly recurrent group which showed a predominance of depressive polarity. conclusions: these data suggest that bipolar patients with a highly recurrent course have significant functional impairment. with the passing of time, bipolar illness tends to be ruled by depressive features. treatment strategies may need to address this issue.