This paper describes two women. The first was admitted to hospital having suddenly, and without adequate reason, developed the idea that a senior married colleague at her workplace had fallen deeply in love with her. The second woman is her mother, who had been admitted to the same hospital twenty-two years earlier with a well systematized delusion that her husband was unfaithful. Both syndromes have been described by de Clérambault as two of the three forms of psychose passionnelle. The present report is intended to clarify the concepts of psychose passionelle and demonstrate the similarities between jealousy and erotomania. We believe these case histories describe the first reported instance of psychose passionnelle in successive generations of one family.