Electrosyneresis (counter-current immunoelectrophoresis) detected the presence of 7 coxsackieviruses and 1 poliovirus in 70 specimens of stools. Identical results were obtained by inoculation of mice and tissue cultures. First screening of specimens was undertaken with a human "standard" gammaglobulin; only specimens precipitating with this reagent contained viral antigens. Hence, especially in children, all negative stools could be excluded from subsequent tests with antiserum pools and monospecific antisera. In our experience, electrosyneresis is a specific method: every type of coxsackievirus and poliovirus types react only with the corresponding monospecific antisera. Electrosyneresis appears to be a sensitive procedure: viral antigens corresponding to 10(4) TCID50/ml can be dtected.