Rotaviruses occur widely among humans and many animal species throughout the world, and are important causes of gastroenteritis. Since their discovery over 30 years ago human rotaviruses have been shown to be the major cause of paediatric diarrhoeal disease morbidity and mortality. (1) The virus will have infected some 90% of children by the age of 3 and practically all children by the age of 5, (2) and accounts for approximately 600 000 deaths worldwide every year. (3) The incidence of rotavirus disease in children is similar in developed and developing countries, but mortality from diarrhoeal disease is higher in the latter, predominantly owing to poor knowledge of oral rehydration therapy and malnutrition. In Africa rotavirus accounts for about a quarter of hospitalisations of children for diarrhoea. (4,5) A study from 15 African countries done to assess epidemiology and disease burden suggests that rotavirus is the most important cause of severe diarrhoea in African children. (4) Public health measures to provide clean water and improved hygiene and sanitation may affect the incidence of diarrhoea caused by bacterial infection, but not that of rotavirus. (4) Vaccines have been shown to be the only means of reducing morbidity and mortality due to rotavirus. (1,5,6) In industrialised countries with good standards of hygiene and clean food and water rotavirus remains the most common cause of diarrhoea-associated hospitalisations among young children. (3) There is an urgent need to develop an effective vaccine to protect against severe rotavirus disease, and data on the incidence of rotavirus infections in Africa and the antigenic and genomic diversity of the rotavirus are required for the design of an effective vaccine strategy.