Using the virus-binding assay and scanning electron microscopy (SEM), influenza A and B type viruses and two paramyxoviruses, parainfluenza (Sendai) and mumps viruses, were found to bind to Group B Streptococcus (GBS), type Ia and II, with the terminal sialyl-galactose linkage, although some viruses detached during the sample processing for SEM, and mumps virus did not bind to GBSIa. Binding of viruses eluted from GBS at 37 degrees C depended on combination of virus and GBS. The biological significance of these findings is discussed.