Patients with paraphilias often also have psychiatric co-morbidity. In this study of a case from an outpatient clinic we discuss the treatment of paraphilia not otherwise specified, characterised by hypersexuality, in a patient with paraphilia and psychiatric co-morbidity. After explaning the diagnosis and treatment plan we describe how the treatment proceeded. We begin by focusing on interventions to tackle the symptoms of obsessive-compulsive disorder and then concentrate more on the patient's hypersexuality and treatment by means of pharmacology. Thereafter we make a more detailed study of the role played by libido-reducing drug in the treatment of the patient's hypersexuality.