There is a widely held perception that cancer is influenced by psychological factors, and that both the onset and progression of the disease are affected by factors such as stress, depression, social isolation and coping style. This article reviews the evidence for the mind-cancer link. Although hundreds of studies have reported on this issue, much of the research has been undermined by methodological weaknesses such as small sample size and failure to control for confounding factors. Many studies have failed to find any association between psychological factors and cancer, and findings of even the high quality studies have been inconsistent. To date there is insufficient evidence to conclude that psychological factors play a significant and direct role in disease processes in cancer.