To examine reductions in diarrhea-associated health care utilization after rotavirus vaccine implementation and to assess direct and indirect effectiveness of vaccination. Retrospective cohort analysis of claims data of commercially insured US children aged <5 years. We examined annual pentavalent (RV5) and monovalent (RV1) rotavirus vaccine coverage. We compared rates of diarrhea-associated health care utilization in prevaccine (2001-2006) versus postvaccine introduction (2007-2011) years, compared rates of diarrhea-associated health care utilization in vaccinated versus unvaccinated children and compared rates in unvaccinated children in postvaccine versus prevaccine years. Among children aged <5 years, RV5 and RV1 rotavirus vaccine coverage rates reached 58% and 5%, respectively, by December 31, 2010. Compared with the average rate of rotavirus-coded hospitalizations in 2001-2006, rates were reduced by 75% in 2007-2008, 60% in 2008-2009, 94% in 2009-2010, and 80% in 2010-2011. Compared with unvaccinated children, in 2010-2011, the rate of rotavirus-coded hospitalizations was reduced by 92% among RV5 recipients and 96% among RV1 recipients. Rotavirus-coded hospitalization rate reductions among RV5 recipients versus unvaccinated children ranged from 87% among <1-year-olds to 81% among 4-year-olds. Compared with prevaccine rates in 2001-2006, rotavirus-coded hospitalization rates among unvaccinated children decreased by 50% in 2007-2008, 77% in 2009-2010, and 25% in 2010-2011. Implementation of rotavirus vaccines has substantially reduced diarrhea health care utilization in US children. Both rotavirus vaccines conferred high protection against rotavirus hospitalizations; RV5 conferred durable protection through the fourth year of life. Vaccination also conferred indirect benefits to unvaccinated children.