Although therapeutic drug monitoring (TDM) has been used in practice, conflicting data on its usefulness in the management of epilepsy have been reported. These results range from identifying no significant differences in patients’ clinical outcomes to determining TDM to be a cost-effective service. Thus, this study was conducted to evaluate the effectiveness of our pharmacist-managed TDM service in helping patients with epilepsy (PWE) to achieve seizure control. This was a retrospective observational study conducted in the TDM Unit of Hospital Keningau, Sabah. Pharmacist-prepared reports issued for 30 subjects with uncontrolled seizures in 2014 were analysed to determine the effectiveness of their recommendations. Effectiveness was measured based on the number of patients who achieved ≥ 50% reduction in seizure frequency and the number of patients with a threemonth seizure-free period. Overall, 80% of the pharmacists’ TDM recommendations were accepted by prescribers. Based on the data collected, 17 (56.67%) subjects had their seizure frequency decreased at least by half, while 11 (36.67%) subjects achieved total remission. However, there was no significant association between acceptance of recommendations and seizure control; although acceptance of pharmacist recommendations was associated with 1.4 times greater odds of achieving seizure control among PWE, this difference was not statistically significant. In conclusion, a pharmacist-managed TDM service was associated with an improvement in seizure control of more than 50% among PWE with unsatisfactory seizure control.