This study examined the effectiveness of giving medical oncologists immediate feedback about cancer patients' self-reported psychosocial well-being in reducing those patients' levels of anxiety, depression, perceived needs and physical symptoms. Cancer patients attending one cancer centre for their first visit were allocated to intervention (n = 42) or control (n = 38) groups. All patients completed a computerized survey assessing their psychosocial well-being while waiting to see the oncologist. Intervention patients' responses were immediately scored and summary reports were placed in each patient's file for follow-up. A total of 48 participants (25 intervention and 23 control) completed the survey four times. Intervention patients who reported a debilitating physical symptom at visit 2 were significantly less likely to report a debilitating physical symptom at visit 3 compared with control patients (OR = 2.8, P = 0.04). Reductions in levels of anxiety, depression and perceived needs among intervention patients were not significantly different to control patients. Repeated collection and immediate feedback of patient-reported health information to oncologists has potential to improve patients' symptom control, but has little impact upon emotional well-being, including those at high risk. Future research should consider providing the feedback to other health professionals and patients, and monitor the impact on the process of individual patient care.