Objective: To determine the prevalence of the accessory sacroiliac joint (ASIJ) on both computed tomography (CT) images and dry bones and ultimately, to contribute to the literature. Materials and Methods: CT images archived in the Radiology department of Gaziantep University Medical Faculty obtained from 145 individuals (104 males and 41 females) as well as 92 sacral bones were examined.  Results:  The prevalence of ASIJ among 92 sacral bones was 15.2%. The ASIJ was more commonly (52%) located at the posterior portion of the SIJ at the level of the second dorsal sacral foramen. In 48% of the bones, ASIJ was identified just above the first dorsal sacral foramen. Unilateral ASIJ was observed in 10.8% and bilateral ASIJ in 4.4% of the sacral bones. On CT images, ASIJ was found in 7.8% of the males and 7.2% of the females. The total prevalence of sacroiliac joint variations was 28.9%, and 6.8% of them were ASIJs. Conclusion: It should be kept in mind that ASIJ may be a source of arthritis and chronic hip pain. The presence of ASIJ should be sought through imaging studies for early diagnosis of ASIJ.