Two hundred couples referred to a sexual problems clinic were assessed in a standardised way for their suitability for sex therapy. The assessment focused on the nature of the sexual dysfunction, motivation for treatment, marital and relationship problems, psychiatric status, and physical problems. Approximately one-third of the couples were found to have significant marital and relationship problems, and more than 30% were suffering from psychiatric disorders, although these were usually of mild to moderate intensity. A third of males and 18% of females were suffering from physical disorders likely to contribute to the sexual dysfunction. Patients who were offered sex therapy and who completed their course of treatment were more likely to show high levels of motivation and an absence of physical disorders, marital relationship problems and psychiatric disorder. There should be careful assessment of couples suffering from sexual dysfunction before specific treatment is offered.