Glycine-HCL buffers at pH 2.0 to pH 4.0 were used to study their effects on dissociation of immunoreagents in direct ELISA. Two spherical viruses, Cucumber mosaic virus (CMV) and Tomato black ring virus (TBRV) were used in polystyrene plates separately and two elongated ones Potato virus Y (PVY) and Potato virus S (PVS) were also used separately in our investigations. Acid buffer between pH 2.0-2.5 dissociate about 50% of the conjugate of CMV and TBRV while PVS and PVY eluted only by 30% even by pH 2.0. Also, virus antigen of elongated viruses could not be eluted. The bond between plate and immunoglobulin G was less affected by acid buffer than other bonds.