This study was designed to identify aerobic bacteria that cause acute supportive tonsillitis and to study their patterns of sensitivity to different antibiotics used in treatment of tonsillitis in Baghdad hospitals. A total of 312 tonsil swabs were collected; 262 swabs from patients suffering from acute supportive tonsillitis in Ear Nose Trachea department, 50 swabs from volunteers who have no tonsil infections (for comparative study among isolates). Sixty two swabs were discharged and the remaining 250 swabs were cultured on blood agar and chocolate agar plates and incubated at 37°C for 24 hours. Isolates were purified by frequent sub culturing and identified on the basis of their morphology, Gram staining, cultural characteristics and biochemical reactions. Streptococcus pyogenes, Streptococcus pneumoniae, Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus intermedius, Haemophilus influenzae and Haemophilus parainfluenzae. Streptococcus pyogenes as the predominant species, whereas Haemophilus parainfluenzae was isolated from only one patient. All bacterial isolates were tested for their sensitivity to a number of antibiotics commonly used in treatment of tonsillitis in Baghdad hospitals by disc diffusion method. Streptococcus and Staphylococcus species were sensitive to Cephalosporin, Ciprofloxacin, Chloramphenicol, Erythromycin and Vancomycin, moderately sensitive to Gentamycin and Penicillin (60%) and resistant to Ampicillin (100%). Haemophilus species were sensitive to Cephalosporin and Chloramphenicol, but resistant to Ciprofloxacin, Gentamycin and Ampicillin.