This article aims to review the effectiveness of mood stabilizers used in the psychopharmacologic treatment of both bipolar disorder and borderline personality disorder. In this context, the overlapping phenomenology of borderline personality disorder and bipolar disorder and the differential diagnosis of clinical features will be also reviewed with the literature. Both disorders can show common features in terms of diagnosis and overlap in phenomenological perspective. Coexistence of both disorders is quite frequent. The nature of mood shifts, types of impulsivity and the longitudinal course of the disorders should be considered to differenciate them. There are findings on the effectiveness of mood stabilizers such as lithium, carbamazepine, oxcarbazepine, sodium valproate or lamotrigine in the treatment of the borderline personality disorder. The differentiation of borderline personality disorder from bipolar disorder is not easy. A very careful evaluation is required. This differentiation may also be useful in terms of treatment. A greater number of research results are available on the effectiveness of valproate and lamotrigine in the treatment of borderline personality disorder. Findings related to other mood stabilizers are insufficient. In the treatment of borderline personality disorder, there is not any drug approved by the official authorities. Psychotherapeutic approaches still retain their important place in the treatment. However, symptom-based approach is proposed in the use of mood stabilizers.