After the introduction of antibiotics, empyema is a rare complication of retropharyngeal abscess caused by acute epiglottitis. But once it occurs, it may be a fatal outcome. Retropharyngeal abscess may spread to mediastinum and pleural cavity along the deep cervical fascia, then it can induce pneumonia, mediastinitis, empyema, and sepsis. Because of its fatal complication, early diagnosis and intensive surgical treatment, such as incision and drainage, is necessary. Now we have a experience of empyema caused by retropharyngeal abscess in a 56-year old diabetic patient with nephropathy. He was admitted to our hospital because of hoarseness and sore throat due to acute epiglottitis. Several days after his admission, he complained of swelling of neck, which was diagnosed as retropharyngeal abscess by the computerized tomography. Retropharyngeal abscess was managed with antibiotics, incision and drainage and culture revealed Peptostreptococcus prevotii. Subsequently empyema developed in his right chest, which was managed with closed thoracotomy, though, he expired due to progression of sepsis.