The paper presents the results of research studies conducted during a lo-year period (1962-1971) with the view to detect certain enteroviruses (Coxsackie) from sewage, river and drinking water samples, and from the filter sand of drinking water-works supplied with river water. The method consisted first in preconcentrating the samples collected on immersed gauze pads, secondly in the concentration of the virus samples by the following methods-used either separately or in parallel: the Amberlite method, the yeast cell and the aluminum hydroxide concentration method. The isolation of A and B Coxasackie viruses averaged 29.12% in the sewage samples and 14.66% in the river water samples. Lower values were found both in aqueduct water and in the filter sand (2 positive samples out of 65 and 3 positive samples out of 39, respectively). A seasonal distribution of the viral incidence was evidenced in the sewage samples with lower value in the river water, while the frequency decreased with the distance from the pollution source. For the lightly contamined waters (river and aqueduct waters) the yeast cell concentration method gave the best results, this method being also the single reliable method for Coxsackie virus isolation from the filter sand samples.