A 19 year- old patient monitored with the diagnosis of Ewing sarcoma underwent thoracentesis to relieve locular effusion detected in the right lung visualized on thorax computed tomography obtained because of the dyspneic complaint of the patient. Thoracentesis revealed the presence of empyema. Gemella haemolysans was isolated in three consecutive pleural fluid culture implemented at determined intervals. According to antibiotic susceptibility tests this agent was found to be susceptible to imipenem, and resistant to amoxicilline/clavulanic acid, ampiciline/sulbactam, tetracycline, ceftazidime, ciprofloxacin and levofloxacin. The patient receiving imipenem treatment according to antibiogram results was discharged upon regression of his?her? clinical and radiological findings.