Abstract Introduction The delay in the diagnosis and treatment of breast cancer has a direct correlation with more advanced stages of the disease and a lower survival rate. These delays represent an urgent situation in developing countries due to their high prevalence. Objective This study aims to determine the time intervals in the diagnosis and treatment of patients with breast cancer in the main public hospital in the city of Tijuana, to identify the mechanisms through which the different population aspects and Hospitals affect the treatment of patients. Methods A descriptive, observational, and retrospective study was conducted, including patients with breast cancer diagnoses treated at the General Hospital Tijuana in the period from January 2019 to December 2019. We used data from the medical record, including dates, demographics, histopathological, and clinical data from each visit. Descriptive statistics were calculated in SPSS V27. Results A total of 154 patients with breast cancer were treated at the TGH during 2019. Of these, 97 patients included in the study, with an average age of 52.34 ± 9.14 years. The patient delay time was higher than three months in 61% of cases. The diagnosis delay time was between 5 and 13 weeks. Conclusion Mexican breast cancer patients, as Latinas in California, are more likely to exhibit late-stage breast cancers at the time of diagnosis and have lower survival rates. Mexico counts an opportunistic or non-organized mammography screening program, leading to considerable delays in the diagnosis of breast cancer, even in border cities near to the US (where some people use multiple healthcare systems). With this context, it is necessary to recommend the creation of an organized screening program based on a more exceptional ability to cover the target population and, therefore, greater effectiveness at the community, as well as more equitable access. Citation Format: Antonio Galindo-Castañeda, Martín Gonzalez-Corral, Luis Garcia-Armas, Oscar Egurrola-Terán, Luis Martínez-Gómez, Jorge Albert Guadarrama-Orozco. Delay time in the diagnosis and treatment of breast cancer in the California-Mexican Border [abstract]. In: Proceedings of the AACR Virtual Conference: Thirteenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2020 Oct 2-4. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(12 Suppl):Abstract nr PO-214.