Objective: Rhinoscleroma, a chronic granulomatous bacterial disease of the nasal mucosa that often extends through the lower respiratory tract, is caused by infection with the gram-negative bacillus Klebsiella rhinoscleromatis (KR). We report the clinicopathology and histology associated with KR infection-induced rhinoscleroma in patients admitted to the Beijing Tongren Hospital over a 30-year period. Methods: The clinical and pathologic features of 40 cases of upper aerodigestive tract infections were retrospectively studied. Histochemical examination of biopsy samples was performed, including periodic acid-Schiff, modified Warthin-Starry, and acid-fast stains. In addition, immunohistochemical staining for CD43, CD20, CD68, and lysozymes was performed in 11 specimens, and 8 specimens were analyzed by transmission electron microscopy. Results: KR infection was confirmed in each of the 40 samples. Twenty-seven patients remained relapse free 1 to 10 years following treatment with antibiotic supplemented in some cases with surgery or radiotherapy, and all 13 cases of relapse were successfully eradicated by the end of treatment. KR infection was localized to phagosomes within Mikulicz cells, as determined by immunohistochemistry and electron microscopy. Significant tissue injury was observed in most cases. Conclusion: Long-term antibiotic therapy successfully eradicated KR infection in all cases. Although late diagnosis was common in this cohort, retrospective examination of biopsy samples suggests that diagnosis can be improved by combining clinical findings with histologic analysis.