OBJECTIVES: Concentrations of some drugs appear to have inappropriate indications or suboptimal timing, particularly in the inpatient setting. It is important to know the concentration of the drug taken because each drug has a minimum and maximum level for best performance. Several studies have documented that the appropriate use of pharmacokinetic drug monitoring, particularly in conjunction with a clinical pharmacokinetic monitoring (CPM) service, is both efficient and cost-effective. The aim of this study is to evaluate the effectiveness of a computerized CPM system which was implemented in a medical center. Indicators of medication outcome were collected prior to and after the CPM system was introduced. METHODS: The drug Digoxin is representative and being evaluated in this study. Several objective indicators were used to estimate cost-effectiveness of this CPM. These included day interval of abnormal serum concentration, costs of laboratory blood test, length of stay and drug cost. RESULTS: After introducing the CPM system, day intervals of abnormality in serum concentration are significantly reduced by 3.53 days/patient. Average length of stay significantly decreases after the CPM, from 32.13 to 27.92 days in average. The cost of laboratory blood test can be saved is US$33.27/patient. In addition, the cost of toxicity therapy was found significantly reduced by US$9.68/patient (US$23.76/patient vs. US$14.09/patient; p<0.05), due to reducing the use of Lidocaine, Phenytoin and anti-diarrhea drugs. Similarly, significant reduction was found as US$9.42/patient (from US$22.82/patient to US$13.41/patient; p<0.05) for the cost of combined therapy in the over-optimal group. CONCLUSION: This study provides the evidence for the effectiveness of the computerized CPM system by several indicators. The implementation of the CPM system is meaningful in pharmaceutical care that can improve quality of patient care as well as enhance patient safety.