OBJECTIVE--To see whether stress could be alleviated in patients being treated for early breast cancer. DESIGN--Controlled randomised trial lasting six weeks. SETTING--Outpatient radiotherapy department in a teaching hospital. PATIENTS--One hundred fifty four women with breast cancer stage I or II after first session of six week course of radiotherapy, of whom 15 dropped out before end of study. INTERVENTION--Patients saw one of two researchers once a week for six weeks. Controls were encouraged to talk about themselves; relaxation group was taught concentration on individual muscle groups; relaxation and imagery group was also taught to imagine peaceful scene of own choice to enhance relaxation. Relaxation and relaxation plus imagery groups were given tape recording repeating instructions and told to practise at least 15 minutes a day. END POINT--Improvement of mood and of depression and anxiety on self rating scales. MEASUREMENTS AND MAIN RESULTS--Initial scores for profile of mood states and Leeds general scales for depression and anxiety were the same in all groups. At six weeks total mood disturbance score was significantly less in the intervention groups, women in the combined intervention group being more relaxed than those receiving relaxation training only; mood in the control group was worse. Women aged 55 and over benefited most. There was no difference in Leeds scores among the groups. CONCLUSIONS--Patients with early breast cancer benefit from relaxation training.