In the discussion of social inequalities in health there has been much debate on the role of medical care. Large differences in cancer incidence and mortality from cancer have been consistently observed. To understand the potential importance of socioeconomic differences in prompt detection and treatment of cancer it is essential to have data on cancer survival. These have been examined less extensively than differences in cancer incidence. We have reviewed 42 studies on social class differences in cancer survival. Twenty-three studies were conducted in North America, and 15 in western European countries. Twenty-three studies were carried out through population-based cancer registries and 17 through hospitals or hospital-based registries. Seven studies examined survival differences for multiple cancer sites. Social class differences in cancer survival appear remarkably general. Patients in low social classes had consistently poorer survival than those in high social classes. The magnitude of the differences for most cancer sites was fairly narrow, with most relative risks falling between 1 and 1.5. The widest differences were observed for cancers of good prognosis and specifically cancers of the female breast, corpus uteri, bladder and colon. The pattern of the social differences in survival did not vary consistently by sex, country, or source of the study population and did not depend on the socioeconomic indicator used.