OBJECTIVE: To determine whether race/ethnicity and sex independently increase risk of respiratory distress syndrome (RDS) in late preterm and term infants. STUDY DESIGN: Using a cohort design, we studied the risk of RDS associated with race/ethnicity and sex in infants with gestational age (GA) 34 to 42 weeks born between 1 January 2000 and 31 December 2009 (n=286 454) within 12 hospitals in the Northern California Kaiser Permanente Medical Care Program. RESULT: Male sex (adjusted odds ratio (aOR) 1.68; 95% confidence interval 1.45 to 1.93) and White race/ethnicity (vs Asians (aOR 0.57; 95% confidence interval 0.47 to 0.70), Blacks (aOR 0.66; 95% confidence interval 0.50 to 0.87), and Hispanics (aOR 0.76; 95% confidence interval 0.64 to 0.90)) independently increase risk for RDS regardless of GA. A GA <39 weeks, operative delivery, maternal diabetes, and chorioamnionitis also increased RDS risk in this cohort. CONCLUSION: Male sex and White race/ethnicity independently increase risk for RDS in late preterm and term infants. Timing of elective delivery should acknowledge these risks.