BACKGROUND Therapeutic drug monitoring (TDM) is the widely used tool in neuropsychiatric disorders. It is a valuable tool for tailoring the dose, preventing adverse drug reactions, and testing the drug adherence, therapeutic nonresponse, pharmacokinetic, and drug-drug interactions. TDM is most useful for individualized pharmacotherapy in bipolar disorders. But there exists a death of information on TDM of mood stabilizers in real-life scenario. Hence, this study aimed to assess the use and indication of TDM for mood stabilizers in a university hospital. METHODS A descriptive, retrospective, study was carried in a university teaching hospital in Dammam metropolitan region of Saudi Arabia. Patients were included in the study if they had a mood stabilizer with serum level drawn between January 2017 to December 2018. The patient list was collected from "QuadraMed" health information system. TDM details such as values of each TDM, reason for the TDM, and number of TDM for 1 year have been documented. RESULTS A total of 200 patients received 242 mood stabilizers during the study period. Gender distribution was almost equal in the study population male (52%) versus female (48%). Average age of the patients was 40 years (range = 17-87 years). A total of 41.5% (n = 83) patients were diagnosed with bipolar type 1. Valproic acid (n = 139 [57.9%]) and lithium (n = 54 [22.3%]) were the most commonly used mood stabilizers. Majority (80%) of the bipolar patients were managed with single mood stabilizers. A total of 613 TDM was ordered for the 200 patients during the study period. The average number of TDM per patient during the study period was 3 (range = 1-39). Validation of the therapeutic level (n = 140), lack of clinical response (n = 51), and change in the dose (n = 34) are the documented reasons for TDM. CONCLUSIONS This study highlights the common and specific reasons for TDM of mood stabilizers in routine clinical practice. More extensive study on a larger sample size in the prospective basis is required to find out the rationality of TDM orders and its outcome for the development of the polices.