Stalking behavior has been associated with several psychotic and non-psychotic mental disorders--most frequently, primitive personality psychopathology regardless of co-occurring psychotic symptomatology. Erotomanic and jealous delusions may be the most clinically and forensically relevant of the psychotic symptoms. However, the psychiatric literature has not well appreciated delusional jealousy as an important contributor to stalking behavior. The case of Mr. L can be conceptualized as one of delusional jealousy in that his jealous delusions, auditory hallucinations, and paranoia dated back to early adulthood. Drugs may also have contributed to his psychosis. However, a clear genetic loading for schizophrenia existed among his first-degree relatives. Findings from this case and the literature analysis suggested that further research needs to focus on several important questions related to delusional jealousy. 53 references (Author abstract modified)