Patients' recollections of their past symptoms, illnesses, and episodes of care are often inconsistent from one inquiry to the next. Patients frequently fail to recall (and therefore underreport) the incidence of previous symptoms and events; tend to combine separate, similar occurrences into a single, generic memory; and falsely recall medical events and symptoms that did not in fact occur. This unreliability of recall is affected by personality characteristics and by the patient's current state at the time of recall. Thus, current anxiety or depression and pain or bodily distress foster the recall of symptoms and events that are not recalled when the patient is more comfortable. Finally, current beliefs about one's health and the nature and causes of one's illness also affect the recall of past symptoms and illness. Physicians can maximize the reliability of the clinical history by (1) noting and taking into account the patient's current physical and emotional state; (2) first establishing historical "anchor points" or memorable milestones; (3) decomposing generic memories by finding features that distinguish them from each other; and (4) recalling the clinical history in retrograde fashion, beginning with the most recent event and working backward.