The first contact of TB (tuberculosis) patients with the health system occurs at the front door and is essential to access to diagnosis. The objective of this study was to identify and analyze patients' first contact with the health system for TB diagnosis in Ribeirão Preto. The study was based on an instrument of the Primary Care Assessment Tool, adapted for TB care in Brazil. Structure interviews were conducted with 100 TB patients diagnosed between June 2006 and July 2007. Of all patients, 61% were referred to the diagnosis place and only 29% sought the service spontaneously; 66% sought for primary care services, and 34% for secondary and tertiary services. Public services diagnosed 89% of all cases, 44% of which were diagnosed in emergency services. A total 88% of patients were not from the area covered by the service. Although patients have sought for primary care services, close to their houses, the diagnosis occurred in secondary and tertiary health care.