A simple and rapid procedure for identifying adenovirus and rotavirus in stool extracts has been developed. The technique is based on polyacrylamide gel electrophoresis of the virus nucleic acid, but sample preparation is straightforward and does not entail phenol extraction or the use of a radioactive label. Furthermore, processing is not influenced by the amount of specimen obtained and is thus suitable for application as a batch testing method. This approach removes the need for specific antisera, which are not readily available since most of these viruses cannot be grown using routine tissue culture procedures. Trials in this laboratory have indicated that the technique is of comparable sensitivity to electron microscopy.