The Gaslight Syndrome, a scenario in which one partner of a conjugal unit attempts to have the other labelled insane and institutionalized, is probably more prevalent than is commonly realized. The essential features are: the presence of a sado-masochistic marital relationship, underlying themes of sexual jealousies and the deliberate attempt by the aggressive partner to terminate the relationship by having the spouse declared mentally ill and hospitalized. Psychiatric identification of the phenomenon should allow earlier recognition of it and hopefully prevent possible infringements of a patient's rights.