Researchers using various psychological measures and instruments have concluded that the personality of remitted bipolars and normal controls are essentially similar. We recently suggested that specific personality traits might be genetic markers for manic-depressive illness. The Tridimensional Personality Questionnaire (TPQ) is a personality questionnaire with heritable subscales and hypothesized anchoring in neurochemistry. We studied the personality of euthymic bipolar manic depressive patients using the TPQ. Subjects were volunteers from the out-patient Lithium Clinic. TPQs were individually administered to 50 euthymic bipolar patients. Persistence is significantly reduced, and harm avoidance and reward dependence significantly increased, compared with U.S. norms. These traits may be part of the genetic diathesis for manic-depressive illness.