A step-wise protocol is described for the treatment of bipolar affective disorder, with emphasis on the use of lithium. The objective of this protocol is to delineate the steps clinicians must consider in monitoring a patient who is receiving treatment for bipolar affective illness. While not covering every aspect of treatment, the protocol does provide the basic steps necessary for care; it is intended for use in conjunction with the clinician's personal expertise. The protocol has also been found useful in the training of residents and students.