There are several major breast cancer guidelines that have been promoted by various health organizations. Arrowhead Regional Medical Center (ARMC) Family Health Centers adopted the current guideline by the U.S. Preventive Services Task Force (USPSTF), which recommends breast cancer screening with mammograms starting at age 50 for low-risk women. This study evaluates the effectiveness of this screening guideline in the selected Hispanic underserved population in San Bernardino, California (CA). This is a retrospective chart review study. Data were reviewed for any female with the confirmed diagnosis of breast cancer at the Family Health Centers between 2009 and 2018. The current study showed that 25% (40 of 160) of women diagnosed with breast cancer in this selected population were less than 50 years old. This finding suggests that high vigilance in breast cancer screening may be necessary in this population.