Aerosols from waste treatment plants were examined with regard to the presence of airborne viruses. For the purpose of a comparative evaluation, two different collecting devices consisting of an electroprecipitator and a special-impinger apparatus were used for extraction and collection of viruses from air samples. The collected suspensions were concentrated and fractionated by means of hydroextraction in combination with a differential centrifugation procedure. After solubilisation of the sedimented material with the anionic detergent, sodium-dodecylsulfate, and following ultrasonic treatment, viral infectivity could be demonstrated in 12 out of 36 examined specimens, after inoculation on BGM cells. The highest virus isolation rates were obtained with the electroprecipitator. Based on the results of investigations of biological, physicochemical as well as antigenic characteristics, the isolated strains revealed to belong to the family of Picornaviridae. According to the results of additional characterization assays, the isolates were identified as Coxsackie-B and ECHO-viruses. The linkage between the occurrence of these viruses and a possible risk of infection for humans remains to be elucidated by further epidemiological studies. However, the results of the present work indicate that, besides of an increased dust and germ concentration in such facilities, there is substantial evidence of increased viral contamination as well. Enteroviruses are generally considered as indicator viruses revealing the presence of viral contaminants in tap water and sewage. As human enteroviruses can be regularly isolated from such aerosols, the detection of these viruses in air samples may also be an appropriate criterion to estimate the amount to which virus concentrations may build up within waste treatment plants.