The prevalence of psychiatric disorder and associated factors has been examined in 139 women with advanced breast cancer. Patients completed a self-report assessment of mood, the Hospital Anxiety and Depression Scale (HAD). They were also interviewed to obtain sociodemographic details, UICC performance status and past psychiatric history. Overall, 35 (25%) scored 11 or above (out of a maximum of 21) on either the anxiety or the depression subscales, or both, of the HAD and were therefore probable cases of anxiety and/or depression. These patients are likely to benefit from psychosocial intervention. Clinical anxiety was unrelated to any sociodemographic or disease related factors. Clinical depression was significantly more prevalent amongst patients in the lower socioeconomic classes (P = 0.01) and those with poor performance status (P = 0.007). Depression can be difficult to detect in patients with advanced breast cancer and these factors may be useful indicators to clinicians of patients at high risk of this disorder.