The pharmacokinetics of ceftazidime after a 1-g bolus dose were studied in six elderly volunteers and 12 young subjects. Serum and urine samples were collected in serial order for 24 h and assayed by high-pressure liquid chromatography. The ceftazidime renal clearance was reduced in elderly subjects, a symptom related to normal aging of the kidneys. The decrease in volume of distribution in the elderly group may be explained by a reduction in total body water and an increase in fat tissue. Dosage adjustment is probably not necessary for otherwise healthy elderly patients requiring ceftazidime.