This study aims to describe the medical itineraries followed by breast cancer women affiliated to the People's Health Insurance in San Luis Potosí, central Mexico. We used an ethnographic approach based on oral histories of 12 women diagnosed with breast cancer in the year prior to the first meeting. Two face-to-face sessions per participant lasting 60 minutes each were conducted followed by a telephone interview. Content and diachronic analyses were used. Three main itineraries were identified: (1) diagnostic process, (2) final diagnosis to treatment, and (3) cancer control and relapse. Findings suggested that infrastructure and human resources to adequately screen and timely diagnose breast cancer were scant and insufficiently trained, respectively. Deferral of medical assessment was related with lack of information about breast cancer consequences, with women being afraid of a positive result, and with economic constraints. The current screening program needs to be redesigned to prevent diagnostic delays, as these seem to explain the high frequency of advanced stages reported at the time of diagnosis.