Psychological responses were measured in a newly diagnosed group of breast cancer patients during their hospital stay for primary surgical treatment by mastectomy. The aim was to assess the extent to which patients responded to the stress of a cancer diagnosis by denying the seriousness of the illness, and how this related to both level of distress and prior delay in seeking treatment. The data indicated that patients who denied the seriousness of a cancer diagnosis experienced significantly less mood disturbance during this period than those who were more accepting of the implications of this diagnosis. These findings suggest that a denial rather than a confrontation-coping-response may effectively reduce the short-term distress experienced during this initial period of hospitalization. Contrary to predictions, we failed to show an association between the length of delay in seeking treatment and denial of the diagnosis.