Observations are made on 740 coagulase positive strains of Staphylococci isolated from pus and exudates of wounds, exudates of joints, serus rxudates cavities, cervix, vagina endometrium, urine, urethra, prostrate, tonsils, throat swabs, sputa, nose, ear pus, eye, blood and glastone. Tabulated results of antibiotic sensitivity against Staphylococcus aureus, Staphylococcus albus and Staphylococcus citreus are given. Drug resistance develops chiefly through simple selection and then a continued multiplication of the naturally occuring sponteneous genetics stable resistant mutants originally present in the clone in the host or the infecting quantum. Even in pure cultures, no two bacteria are exactly like which accounts for competitive advantage. The paper reports that while 55 p.c. of the penicillin resistant strains of Staphylococci were resistant to streptomycin, only 21% of the penicilling sensitive strains were resistant also to streptomycin. 35% of the Penicilling resistant strains were resistant also to Reverine while only 8% of the penicillin sensitive strains were resistant to Reverine. The behaviour of different Streptococci against various antibiotics has also been dealt with in detail.