• Clinicians are being increasingly asked to make clinical judgments on the basis of serum drug concentrations. The interpretation of these measurements in the clinical setting can be aided by a basic understanding of pharmacokinetics. By relating the dose of a drug to a serum concentration under known conditions, pharmacokinetic values may be calculated to assess the validity of the measured serum concentration. To appreciate the normal range and factors that may influence these pharmacokinetic values, the pharmacokinetic article is a valuable resource. A second value to these references is the establishment of reliable methods to achieve desired concentrations on the basis of measured values. By learning some basic definitions, the reader will be better prepared to deal with the interpretation of clinically relevant data in the literature and in the clinical setting.