Rotavirus is the leading cause of severe gastroenteritis in children aged <5 years worldwide. In February 2006, a new rotavirus vaccine, RotaTeq (Merck and Co., West Point, Pennsylvania), was licensed in the United States, and the Advisory Committee on Immunization Practices (ACIP) recommended it for routine vaccination of U.S. infants with 3 doses, administered orally at ages 2, 4, and 6 months. Because a previous rotavirus vaccine, Rotashield (Wyeth Laboratories, Marietta, Pennsylvania), was withdrawn from the U.S. market in 1999 after postmarketing surveillance identified an association with intussusception (a rare type of bowel obstruction), the safety of RotaTeq was evaluated in a prelicensure clinical trial involving 71,725 infants who received either vaccine or placebo. In this controlled trial, no statistically significant elevated risk for intussusception was observed within a 42-day period after RotaTeq vaccination. However, postmarketing monitoring for intussusception after RotaTeq vaccination is necessary because of possible differences in the characteristics of infants who received the vaccine in routine use compared with the infants in the clinical trials. Also, the large numbers of infants being vaccinated provides an opportunity to detect intussusception occurring at a low rate after vaccination. This report presents data from the first year of postmarketing monitoring for intussusception after RotaTeq vaccination in the United States, with particular focus on all intussusception reports received by the Vaccine Adverse Event Reporting System (VAERS) during February 1, 2006-February 15, 2007. As of February 15, 2007, postmarketing surveillance did not suggest association of RotaTeq vaccination with intussusception. CDC reaffirms vaccine policy recommendations to routinely vaccinate U.S. infants with RotaTeq at ages 2, 4, and 6 months.