In Mexico, breast cancer is the leading cancer-related death among women and most cases are diagnosed at advanced stages (50-60%). We hypothesized health system factors could be partly responsible for this delay and performed a prospective review of 166 new breast cases at a major public hospital in Mexico City. Our analysis confirmed the prevalence of locally advanced and metastatic disease (47% of patients). A subset analysis of 32 women with confirmed stage I-IIIC breast cancer found an average time interval of 1.8 months from symptom onset to first primary care consultation (PCC), with an additional 6.6 months from first PCC to confirmed diagnosis, and 0.6 months from diagnosis to treatment initiation. Patients underwent an average of 7.9 clinic visits before confirmed diagnosis. Findings suggest that protracted referral time from primary to specialty care accounts for the bulk of delay, with earlier stage patients experiencing longer delays. These findings reveal a critical need for further study and exploration of interventions.