Rotavirus vaccines were licensed in Spain between late 2006 and early 2007. Rotavirus vaccination was recommended but not reimbursed by the Spanish National Health System. Significant coverage rates have been reached in Galicia, with an average of 47% since the period July 2007-June 2008. We aim to explore eventual variations in the incidence of hospitalizations for acute gastroenteritis (AGE) among children < 5 y of age before and after vaccine introduction. The annual and monthly hospitalization rates for rotavirus-related AGE and all cause AGE, before and after rotavirus vaccine introduction, were calculated by using the official surveillance system for hospital data. The annual hospitalization rates for rotavirus-related AGE in children < 5 y of age decreased by 14.8% for the period July 2008 to June 2009 and by 44.5% for the period July 2009 to June 2010 as compared with the median rate of the pre-vaccination period (July 2003 to June 2007). The corresponding decreases for all cause AGE were 29.9% and 49.0%, respectively. In children < 12 mo of age a more marked decrease was observed. Compared with pre-vaccination years, a decrease in rotavirus-related and all cause AGE hospitalization rates was observed, with a greater decline in the July 2009 to June 2010 period.