Although many side-effects of radiotherapy (RT) are physical, previous studies have shown that patients, when treated with RT, also experience psychological problems. This review describes the psychological functioning of cancer patients prior to, during, and after RT. Moreover, we examined whether medical factors are related to psychological functioning. Using Medline and Psychlit databases over the period 1980-2002, 45 articles were studied for this review. Although some global trends were found, studies revealed great variability in psychological functioning prior to, during, and after RT. Longitudinal studies should include pre-, during, and post-RT assessments of psychological functioning and also take into account the previous psychological stability of the patient.