In order to survey patients' views on reference to clinical data for research purposes, an anonymous self-administered questionnaire was distributed to Aichi Cancer Center Hospital patients in 1995. All eligible first-visit outpatients (97 persons), randomly selected revisit outpatients (99 persons), and all eligible inpatients in a good condition at discharge except six cases (97 persons), responded to the questionnaire. Out of 293 patients (115 males, 174 females and 4 unspecified), 85.3% (standard error 2.1%) considered that hospitals should make active efforts to improve their health care and treatment skills. And 88.1% (standard error 1.9%) answered that reference to their own clinical data to improve health care and treatment skills was "preferable" or "don't mind".