Quantitative evaluation of the therapeutic drug monitoring services (TDMS) provided in Kyushu University Hospital from August 1981 to April 1989 was performed. Since 1982, the annual number of assay requests was about 4300-4400, but the annual number of clinical pharmacokinetic consultation services (CPCS) showed a tendency to increase. Antiepileptics were the drugs for which CPCS were most often performed (26.3 percent of the population given drugs for which TDMS was available); digoxin, lithium, and theophylline followed. Preparation of one consultation required 1.5-2.5 hours. Our TDMS team consists of eight members. In 1988, the average time per week spent for CPCS and TDMS was 8.2 and 11.3 hours per member, respectively. Thus, the number of pharmacists performing CPCS and TDMS was 1.2 and 1.7 full-time equivalents, respectively.