This paper has reviewed the literature on bereavement and, with particular emphasis on the authors' own work, describes three syndromes which seem to be related to the nonresolution of distinct phases of the grief process. The possibility of unresolved grief should receive a high index of suspicion for the patient with otherwise unexplainable depression, chronic illness behavior, or symptoms similar to those of a deceased relative or friend. When any of these syndromes are identified, it is useful to ask the patient who he has lost, how he has lost them, how he felt about the loss, whether he felt that he grieved, whether he still cries or feels the need to cry, and whether he has adjusted. The answer to these questions--both verbal and nonverbal--will help identify unresolved grief, when present, and may be a guide to specific interventions. On the other hand, our studies have suggested that unresolved grief is a somewhat overly simplistic concept. Most, if not all, people never totally resolve their grief; significant aspects of the bereavement process go on for years after the loss, even in otherwise normal patients. For some, identification syndromes continue. Others may continue to feel the presence of the deceased or have daily visions of him or her. Still others may feel pain, anger, and guilt for years after the death. It is still unclear at what point and to what degree these behaviors and symptoms become medical or psychiatric concerns and become pathological or predispose to serious medical, psychological, or social complications. Investigations into these unreported areas have been initiated and, we trust, will lead to clinically useful answers.