The House of Commons Select Committee on Science and Technology 2000 state that currently less than 5% of adult patients with solid tumours are entered into clinical trials. They recommend that increasing the number of adult cancer patients entering clinical trials must become a high priority. Health-care providers need to prepare themselves for this proposed increase in trial participants by assessing the current status of care and implementing changes within the current infrastructure to provide optimal holistic care. Cancer can change a patient's life either for better or for worse. At one extreme, having cancer leads to enhanced appreciation of life and closer bonds with others. However, at the other extreme, cancer combined with its treatment is viewed as an event that evokes distress and emotional anguish taxing the individual's ability to cope. In the last 25 years, owing to the advent of clinical trials, progress has been made in cancer treatment. Clinical trials may be hailed as the saviour to many therapeutic dilemmas. Treatments are now available which can offer patients hope of cure. Nevertheless, many participants may fear, for the purpose of research, that they may be assigned to less than optimal therapy or that their care will be carried out in a sterile scientific atmosphere devoid of humane and personal consideration. These and other reasons may cause unacceptable personal distress that overrides the potential therapeutic gain. Cancer diagnosis coupled with the ramifications of clinical trial involvement can have significant psychological implications. They may trigger the onset of a mood disorder or exacerbate a present symptom. This article will identify mood disorders in the cancer population, focus on the participants' needs in the clinical trial arena and investigate the influence trial participation has on psychological status.