In countries in which rotavirus vaccines have been introduced for young infants, the incidence of rotavirus infections has dramatically decreased. This report presents an outbreak of rotavirus gastroenteritis among travelers. Data regarding the long-term protective effect of rotavirus vaccines after years of vaccination are scarce. A Japanese group of 14 children and nine adults traveled to Malaysia over 4 weeks. During travel, 15 of 23 patients developed gastroenteritis symptoms (Figure 1). Stool samples were collected from two symptomatic patients that tested positive for rotavirus. None of the five members with a history of rotavirus gastroenteritis developed symptoms. Nine of the 10 vaccinated children developed symptoms of acute gastroenteritis without the need for hospitalization. The only child without a history of vaccination or infection developed acute gastroenteritis and required hospitalization for continuous intravenous hydration. While individuals with a history of infection did not develop acute gastroenteritis, the protective effects of vaccination against symptomatic infection did not sustain long. This indicates the potential need for a booster dose of the rotavirus vaccine for travelers to rotavirus-endemic countries.