Dr. Alice Hamilton (1869-1970) was a pioneer in industrial medicine, a new discipline that emerged with a new interest in working conditions and occupational hazards within an era of unprecedented industrial growth. From various sources, including her reports after she visited Arizona copper belt in 1919, my paper emphasizes the innovation of Hamilton's approach,"shoeleather epidemiology". She went to the source of information in workshops, plants and construction sites, observed the very concrete part of industrial work, interviewed many stakeholders in and around the workplace, making a methodological toolbox for industrial surveys. Her method combined an old medical practice (the medical inquiry) and a new clinical field (the plant) and placed the worker as a patient in the core of the issue of occupational health and safety.