The present study investigated two classes of depressed patients. Unipolar depression patients (20) and bipolar ones (18) to recognize differences between them in brain activity, stress endurance, and some personality traits (five factors of personality traits type including neuroticism, extroversion, experience, acceptance, cautiousness. Electroencephalogram (EEg) scale of stressful life situations, and big five factors Scale were applied. Findings showed significant differences between the two samples in the rate of stress endurance (higher) in the unipolar, lower in bipolar sample. Electroencephalogram revealed variance in brain electrical activity with deviation rate in the diagram higher abnormalities of bipolar individuals. Significant differences were found denoting higher scores in neuroticism and cautiousness of unipolar patients.