['Metropolitan Edmonton, Canada.', 'To determine 1) the pre-diagnosis emergency department utilization history of urban tuberculosis patients, and 2) the resource and outcome implications of emergency department utilization by tuberculosis patients pre-diagnosis.', 'Nested case (emergency department attendee) control (non-emergency department attendee) study of a retrospective cohort of tuberculosis patients.', 'All tuberculosis notifications, 1994 through 1998.', 'Emergency department utilization during the 6 months antedating the diagnosis and emergency department attendee characteristics; for those notified in 1997 and 1998, hospitalizations, nosocomial infectiousness time, and health care costs.', 'Of 250 cases of tuberculosis, 117 (47%) made a total of 258 pre-diagnosis emergency department visits. Emergency department use increased the nearer the patient was to diagnosis. Emergency department attendees were more likely to be older, to have smear and/or culture positive respiratory disease, to have a risk factor for progression of infection to disease, and to have a fatal outcome. In 1997 and 1998, emergency department throughput accounted for 70% of all hospitalization days, 95% of all source case nosocomial infectiousness time, and most health care costs of tuberculosis patients pre-diagnosis.'] Is the emergency department a determinant point of contact of tuberculosis patients prior to diagnosis?