The topic of large mucoid plug of tracheobronchus simulating a tumor lacks scientific research and publication. We report such a case presenting as a pseudo-tumor in an elderly population. The plug was easily removed with a flexible bronchoscope. Microscopically, neither malignant cells nor microbial agents were present in the mucoid plug, confirming the diagnosis of a mucoid pseudotumor. If a collection of mucus, indistinguishable from a true tumor, is detected in the tracheobronchial tree particularly on CT scan, we should consider performing bronchoscopy, as such tracheobronchial mucoid pseudotumor may be distinguished from true tumors by this procedure.