We used OPT to estimate individual and population pharmacokinetics for carbamazepine (CBZ) in Malaysian epileptic patients attending our Neurology Clinic. We noted that plasma CBZ concentrations and clearances correlated poorly with daily doses and body weights respectively but we found the values for clearance, volumes of distribution, elimination rate constants and half lives to be in good agreement with earlier reports. We conclude that OPT is a simple yet useful program to derive individual and population pharmacokinetic parameters for CBZ for use in dosage adjustments. We also conclude that although the Malaysian population do not differ substantially in handling CBZ, available data for the pharmacokinetic parameters must be used cautiously in applying it to the therapeutic drug monitoring for CBZ in our patients.