Introduction: Appendicitis is one of the most common surgical emergencies. In spite of the relatively high rate of negative appendectomy, as a result of miss diagnosis, uncertainty of diagnosis still continues to challenge physicians. The objective of this prospective study was to investigate the role of 99mTc-Ubiquicidin (UBI) scintigraphy in the diagnosis of acute appendicitis and to compare 99mTc-UBI scintigraphy with 99mTc-IgG scintigraphy. Methods: Twelve patients with right lower quadrant pain and suspicious of acute appendicitis were referred to the nuclear medicine imaging center. Radionuclide imaging was performed with 99mTc-UBI in 8 and 99mTc-IgG in 4 patients. Ultrasonography, Alvarado scoring and histopathological examinations were also performed as additional diagnostic tests. Results: Reports from 99mTc-IgG and 99mTc-UBI scintigraphies of all patients were negative. Conclusion: This study may conclude that 99mTc-IgG scintigraphy and 99mTc-UBI scintigraphy in the detection of appendicitis do not have adequate efficacy. However, in order to better evaluate 99mTc-IgG and 99mTc-UBI scintigraphy, a comprehensive study on a large number of patients with clinical suspicious of acute appendicitis would be more helpful
