In the United States, infant mortality risks among Hispanics have not been previously evaluated at the national level. We used the 1983 and 1984 national Linked Birth and Infant Death data sets to compare infant mortality risks among single-delivery infants of Hispanic descent with those among single-delivery infants of non-Hispanic whites (the reference group). We also included the 1983 and 1984 linked birth cohort for single-delivery infants in Puerto Rico. Among all Hispanic groups, the neonatal (less than 28 days) mortality risk was higher among Puerto Rican islanders (relative risk [RR] = 2.3) and continental Puerto Ricans (RR = 1.5) and lower among Cuban-Americans (RR = 1.0) and Mexican-Americans (RR = 1.0). The postneonatal mortality risk (28 to 364 days) was highest among continental Puerto Ricans (RR = 1.2) and lowest among Cuban-Americans (RR = 0.6). Our study underscores the heterogeneity of the Hispanic population in the United States and suggests that interventions to prevent infant mortality be tailored to ethnic-specific risk factors and outcomes.