The present objective was to estimate the association between childhood blood lead concentrations (BLC) and clinical diagnoses of influenza or pneumonia among a large, low-income, underrepresented cohort of children using a retrospective design. Medical records were pulled from the Temple University Hospital System (TUHS) located in inner-city Philadelphia, PA from 2010 to 2020. All children ≤14 years of age with an available lead value in their medical records were included in the analysis (N = 14,217). Lead exposure was measured via BLC as reported in the medical records through screening practices. Respiratory outcomes, influenza and pneumonia, were measured from ICD codes. Log-binomial regression models were fit to estimate the prevalence ratios and 95 % confidence intervals for the associations between BLC and influenza or pneumonia. Poisson regression models were fit to estimate the associations between BLC and counts of influenza or pneumonia recurrence. Additional models examined sexually dimorphic associations between BLC and outcomes. Compared to children with a BLC <
1 μg/dL, children with a BLC of 1-3.4 μg/dL had 172 % higher risk (95 % CI: 1.74, 4.59), and children with a BLC ≥3.5 μg/dL had 101 % higher risk (95 % CI: 1.19, 3.39) of pneumonia diagnosis. No statistically significant findings were observed for influenza. Risk for pneumonia was higher among males compared to females, and risk for influenza was stronger among females. Observed findings indicate that underrepresented, impoverished children are at high-risk for these associations, indicating significant public health and clinical implications.