The progress made in the last few years in methods for direct detection of viruses in clinical samples, without the need for in vitro culture, suggests that they will be applicable to at least some types of environmental samples. The methods for detecting viral antigen include: radio-immunoassay, enzyme immunoassay, agglutination tests, fluorescent antibody techniques and electron microscopic procedures. The use of probes for detecting viral nucleic acid has recently sparked considerable interest. The current status of these methods and potential means for improving them are presented in the report.