The need for safe and effective vaccines to reduce morbidity and mortality caused by rotavirus gastroenteritis in children is well-known. A live attenuated monovalent rotavirus vaccine (Rotarix) containing human rotavirus strain RIX4414 of G1P1A P[8] specificity is being developed to meet the global need. An overview of RIX4414 trials in developed and developing settings is presented for 3 selected trials conducted in Finland (pilot study), Latin America (Brazil, Mexico and Venezuela) and Singapore involving 5024 infants. The vaccine was well-tolerated, with no increase in any solicited symptoms as compared with the placebo. After 2 doses, 61-91% of vaccinated infants developed rotavirus-specific IgA antibodies. There was no interference with immunogenicity of coadministered routine pediatric vaccines. Rotarix significantly reduced rotavirus gastroenteritis episodes and rotavirus-related hospitalizations in vaccinated infants compared with placebo recipients (P < 0.05). Vaccine efficacy was observed against severe rotavirus gastroenteritis caused by G1 and non-G1 types including the emerging G9 type (P < 0.05) in Latin America. These results show prospects for widespread use of Rotarix to reduce rotavirus disease burden and warrant continued worldwide evaluation.