Apart from the use of oral rehydration solution, there are currently no treatment modalities for rotavirus induced diarrhoea, which is particularly relevant to developing countries. Fragments derived from llama heavy chain antibodies were previously shown to be highly stable, efficiently produced in yeast and exhibiting high epitope specific affinity. We now aim to demonstrate that these antibody fragments are capable of reducing morbidity of rotavirus induced diarrhoea. Here we show the isolation of rotavirus specific antibody fragments and their capability of reducing the morbidity of rotavirus induced diarrhoea in vivo in mice. They could provide a treatment modality for the moderation of human rotavirus infections having a significant impact on the course of an often fatal childhood disease.