Sex remains an important contributor to quality of life in many patients with chronic illness and their partners. The effects of chronic illness on sexuality are multifactorial and can impact on all phases of sexual response. Sexual dysfunction and dissatisfaction in chronically ill patients are underdetected and undertreated because of barriers to doctor-patient discussion about sex and lack of medical training in human sexuality. For doctors to become more motivated to broach the topic of sex, they need to recognise that people may be sexually interested even though they are old, ill or disabled. The PLISSIT model provides a graded counselling approach that allows doctors to deal with sexual issues at their own level of expertise and comfort.