OBJECTIVE: The objective of the study was to examine the rates of gestational diabetes mellitus (GDM) associated with both maternal and paternal race/ethnicity. STUDY DESIGN: This was a retrospective cohort study of all women delivered within a managed care network. Rates of GDM were calculated for maternal, paternal, and combined race/ethnicity. RESULTS: Among the 139,848 women with identified race/ethnicity, Asians had the highest rate (P < .001) of GDM (6.8%) as compared with whites (3.4%), African Americans (3.2%), and Hispanics (4.9%). When examining race/ethnicity controlling for potential confounders, we found that the rates of GDM were higher among Asian (adjusted odds ratio [aOR], 1.5; 95% confidence interval [CI], 1.4-1.6) and Hispanic (aOR, 1.2; 95% CI, 1.1-1.4) women as well as Asian (aOR, 1.4; 95% CI, 1.3-1.5) and Hispanic (aOR, 1.3; 95% CI, 1.2-1.4) men as compared with their white counterparts. CONCLUSION: We found that rates of GDM are affected by both maternal and paternal race/ethnicity. In both Asians and Hispanics, maternal and paternal race are equally associated with an increase in GDM. These differences may inform further investigation of the pathophysiology of GDM.