A study was undertaken to assess the importance of systematically recording occupational histories of patients admitted to an internal medicine unit of a university hospital. Detailed information on current and past employment was obtained with questionnaires and in personal interviews from 200 inpatients over a 12-month period. Twenty-one patients (10.5%) were considered to have a "primary illness" (condition causing hospital admission) probably (4.5%) or possibly (6%) related to their current or previous occupation. From the 786 primary and secondary illness and medical antecedents diagnosed for the 200 patients examined, 70 illnesses of 55 patients were considered probably or possibly related to current or previous occupation. This pilot study emphasizes the need for accurate occupational records for patients in an internal medicine ward. This task is best performed by an appropriately trained occupational physician.