Objective: To determine the value of a newly developed dot-blot hybridization assay for the detection of stool viruses in patients with suspected infective diarrhoea.Design: Seven hundred and twenty-seven patients with diarrhoea acquired in the community were surveyed and after exclusion of bacterial pathogens, stools were examined by electron microscopy and dot-blot hybridization for the presence of viruses.Results: Astrovirus and adenovirus types 40 and 41 were found in 1.1 and 1.5%, respectively, of stools examined by dot-blot assay. No definitive diagnosis of astrovirus or Norwalk virus could be made by electron microscopy and fewer adenoviruses were detected, although it provided the only means of detecting rotaviruses.Conclusion: When the results of dot-blot hybridization and electron microscopy were combined, viruses were implicated in 10% of all stool samples analysed.