Risk of cancer mortality from 1973 to 1985 in persons born in the Indian subcontinent who migrated to England and Wales was analysed by ethnicity, and compared with cancer mortality in the England and Wales native population, using data from England and Wales death certificates. There were substantial highly significant raised risks in Indian ethnic migrants for cancers of the mouth and pharynx, gall bladder, and liver in each sex, larynx and thyroid in males, and oesophagus in females. There were also substantial raised risks in these migrants of each sex for non-Hodgkin's lymphoma and myeloma. For the mouth and pharynx, and liver in each sex, and gall bladder in females, there were also raised risks of lesser magnitude in British ethnic migrants. For colon and rectal cancer and cutaneous melanoma in each sex, ovarian cancer in women and bladder cancer in men, there were appreciable significantly reduced risks in the Indian ethnic migrants not shared by those of British ethnicity. Appreciable raised risks in British ethnic migrants not shared by those of Indian ethnicity occurred for nasopharyngeal cancer in males, soft tissue malignancy in both sexes and non-melanoma skin cancer in males. In migrants of both ethnicities there were appreciable significantly raised risks in each sex for leukaemia and decreased risks in each sex for gastric cancer, for lung cancer except in females of British ethnicity and in males for testicular cancer. The results suggest the need for public health measures to combat the high risks of oral and pharyngeal cancers and liver cancer in the Indian ethnic immigrant population of England and Wales, by prevention of betel quid chewing and hepatitis transmission respectively. The data also imply that early exposures or early acquired behaviours in India, or exposures during migration, may increase the risk of leukaemia and reduce the risks of gastric and testicular cancers in the migrants irrespective of their ethnicity. Aetiological studies would be worthwhile to investigate the reasons for the sizeable decreased risk of colon and rectal cancer and increased risk of gall bladder cancer in each sex and the increased risk of thyroid and laryngeal cancer in males and oesophageal cancer in females of Indian ethnicity but not of British ethnicity who have migrated from the Indian subcontinent.