SEVERAL STUDIES reported from this hospital during the past decade have demonstrated a steadily increasing incidence of pathogenic staphylococcic resistant to the antibiotics that have been most frequently used. The stains isolated during 1955 and 1958 were also subjected to phage typing, which showed the most prevalent type to be 80/81, previously typed as 42B/52/81. Since staphylococcal infections continued to be a problem of increasing importance in this, as in other hospitals, additional studies were carried out on strains collected during 1959-1960 from clinical lesions of hospitalized patients as well as from outpatient cases and from autopsies. All of these strains as well as those still available from previous studies were subjected to phage typing with the same standard set of phages used in 1958.1 Materials and Methods Strains of Staphylococcus aureus.— The following collections of strains, all of them coagulase positive, are included in the present