Objective: This article assesses normal appendix vermiformis morphology in the adult age group by computed tomography (CT). Material and Methods: A total amount of 256 cases who had a clinical suspicion of urolithiasis and underwent abdominal- pelvic non- enhanced CT were enrolled in the study. Appendiceal diameter, wall thickness, intraluminal content, and the presence of an appendicolith were evaluated. Variables summarized by descriptive statistics. Groups were compared using the chi-square test and student t-test. Results: The mean diameter of the appendix was 6.5 ± 1.2 mm (range, 3.1-9.7 mm) in all cases. Intraluminal air content detected in 199 (77.7%) cases. In 57 (22.3%) cases without air within the lumen, the appendix was evaluated as collapsed or isodense. Mean appendix diameter was 6.7 ± 1.1 mm in cases with air in the lumen and the mean appendix diameter was 5.8 ± 1.3 mm in cases with isodense or collapsed appearances (p < 0.001). Mean wall thickness of appendix determined as 1.7 ± 0.3 mm (range, 0.9-3.1 mm). Appendicolith was detected in seven (2.7%) cases. Conclusion: In the presence of air in the appendiceal lumen, the increase in diameter can be interpreted normal unless not accompanied by inflammatory findings. It should be kept in mind that normal appendix diameter may be 6 mm or above when the intraluminal content of the appendix could not be distinguished.