The bipolar disorder is often misdiagnosed in particular among outpatients with recurrent depression. Indeed, this work confirmed that the unrecognised bipolar disorder is common among depressed outpatients, which were younger, unemployed, single or divorced with a low socio-economic level. These socio-demographics data gives us an idea about the disability experienced by the unknown bipolar patients. Also, we demonstrate that the under-diagnosis bipolar disorder was associated with the earliest onset age of a depressive episode and it was more prevalent in depressed patients with suicidal ideation and suicide attempts. These factors should be taken into account when we screen for the unknowm bipolar disorder, especially type II to improve the early diagnosis and the quality of life of these patients.