Computer programs for drug dosage adjustment may be fixed, adaptive or empirical.The aminoglycoside antibiotic dosage requirements of individual patients are relatively predictable, and it seems to be adequate to assume that volume of distribution is a fixed proportion of body weight and that renal clearance is a fixed proportion of creatinine clearance. This approach has been less successful with digoxin because patient compliance, the proportion absorbed and liver clearance are not yet predictable. Accordingly, adaptive programs have been developed which use feedback from drug concentration measurements to predict the future dosage needs of the patient.When individual needs are known for a large patient group it becomes possible to predict the dosage requirements of a new patient from the same population by empirical methods. Computer programs for dosage adjustment will not be widely used until their scope is increased and objective evidence of clinical benefit is obtained.