Acute appendicitis is the most frequent appendiceal disease, but some chronic inflammatory conditions can mimic it on computed tomography (CT). We recently experienced two rare cases of appendiceal conditions, which were uncommon to our radiologists and clinicians. This condition is called fibrous obliteration of the appendix, which is a condition that involves replacement of the mucosa and submucosa with fibrotic tissues. Due to similar clinical symptoms and CT findings, fibrous obliteration of the appendix can easily be mistaken as an acute appendicitis. Here, we introduce the symptoms, laboratory results, CT findings, and histological examination findings of two adult patients with fibrous obliteration of the appendix.