In acute Staphylococcal infections, antimicrobial drug therapy must often be initiated before culture results and antibiotic susceptibility testing are completed. Three hundred and ten cultures of coagulase-positive Staphylococcus aureus were tested for antibiotic sensitivity by the Kirby-Bauer method at the Nemazee Hospital in Shiraz, Iran. The overall resistance to penicillin G was 97.10% whereas over 99% of the isolated Staphylococci were sensitive to the penicillinase-resistance penicillin cloxacillin. A penicillinase-resistant penicillin should therefore be used in the initial management of all serious Staphylococcal infections until the organism responsible for infection can be shown to be specifically sensitive to penicillin G.