We measured the type-specific incidence of paediatric rotavirus diarrhoea in an area of northern Ghana. Over 1 year, diarrhoea 1717 episodes were identified, of which 677 (39%) were positive for rotavirus. Risk factors for rotavirus infection included old age, wasting, high Vesikari score and the episode occurring in the dry season. Rotavirus-positive episodes tended to be more acute, causing vomiting and greater dehydration, and were more likely to require hospitalization. The incidence was 0.089 episodes per person-year for all diarrhoea, and 0.035 for rotavirus diarrhoea. The observed incidence decreased markedly with distance from the nearest health centre, suggesting a large unobserved burden. G2P[6], G3P[4] and G9P[8] made up more than half the genotypes detected, but the remainder were diverse. There is a large burden of rotavirus diarrhoea, but the effectiveness of future vaccines could be diluted by the high polymorphism of the virus, and the difficulty of reaching remote populations.