This study aimed to evaluate the association between intrapartum antibiotics (IABX) and asthma and allergic rhinitis among children by ages 6, 8 and 10 years. Retrospective cohort. Data were collected though Kaiser Permanente Northern California’s (KPNC) integrated healthcare system. Children were eligible if they were born in a KPNC hospital between 1997 and 2012 and stayed enrolled through age 6. Modified Poisson regressions with robust error variances were used to estimate risk ratios for IABX and each outcome at each follow-up age during two separate time periods: 1997-2004 (n = 91 739) and 2005-2012 (n = 108 314). Asthma and allergic rhinitis by ages 6, 8 and 10. The proportion of women receiving IABX increased drastically over the study period (from 4% in 1997 to 49% in 2011), while the incidence of asthma (8%) and allergic rhinitis (6%) stayed relatively stable. In adjusted models, risk ratios for the association between IABX and asthma and allergic rhinitis were largely compatible with the null, with some slightly elevated risk ratios observed. For births from 1997 to 2004, risk ratios for asthma were 1.08 (95% CI 1.00-1.17) at age 6, 1.05 (95% CI 0.97-1.15) at age 8, and 1.08 (95% CI 0.99-1.18) at age 10. For births from 2005 to 2012, risk ratios were 1.00 (95% CI 0.95-1.04) at age 6, 1.07 (95% CI 1.01-1.12) at age 8, and 1.11 (95% CI 1.03-1.20) at age 10. Exposure to intrapartum antibiotics is not a strong predictor of childhood asthma or allergic rhinitis risk. Exposure to intrapartum antibiotics is not a strong predictor of childhood asthma or allergic rhinitis risk.