BACKGROUND: Concern is widespread that the public's and participants' trust in medical research is threatened, but few empirical measures of research trust exist. This project aims to enable more rigorous study of researcher trust by developing and testing appropriate survey measures. METHODS: Survey items were developed based on a conceptual model of the primary domains of researcher trust (safety, fidelity, honesty, global trust). Pilot testing was conducted on a regional convenience sample of adults (n = 124). Exploratory factor analyses of the data were performed, and an item selection procedure reduced the number of survey questions. A final set of 12 items was validated, and a 4-item short version of the researcher trust scale was selected and tested in a national web-based survey of asthma and diabetes patients (n = 3623). Further factor analysis and validation were performed on this larger sample. RESULTS: Both the full and short scales have a single-factor structure with acceptable internal reliability (alphas of 0.87 [12 items] and 0.72 [4 items]). Trust in physician researchers and trust in medical researchers generally were found not to be separate constructs. In the national sample, the short scale was positively associated with better health status, prior participation in medical research, and willingness to participate in a hypothetical medical research study, and negatively associated with African-American race and higher education. CONCLUSIONS: Trust in medical researchers is a measurable single-factor construct including trust in safety, researcher fidelity, and honesty. This new scale provides an empirical tool for informing the ethics and public policy of medical research.