Reinfections caused by rotavirus were detected in 7(9.2%) out of 76 children from Belém, Pará, Brazil, followed up since birth to twenty months of age. Rotavirus subgrupo II ("long pattern") in both infections was noted in five children. In two, the first infection was associated with subgroup II and the second ones with a strain whose electropherotype was not determined. Six different electropherotypes were observed in these cases and no homologous profiles were associated with reinfections in the same child. The lenght of time between the two infections ranged from six to 19 months. Diarrhoea in both infections was. observed in five children; in two of them, however, first episodes were asymptomatic. Seroconversions to rotavirus were noted in six of the seven children, during reinfection. In the first infections, however, seroconversion was observed in only one case (Paciente F).