The coagulation kinetics of the dispersions of the A/Mississippi/1/85 influenza virus strain in NaCl solutions was studied at various pH values via the flow ultramicroscopy technique. Results obtained for different preparation procedures of virus dispersion are compared and conditions resulted to “superfast” (faster than according to Smoluchowski’s theory) coagulation are determined. Common generalities inherent to the process of superfast coagulation of the A/Mississippi/1/85 influenza virus strain and strains previously studied are found.