Confusion surrounding low back pain syndrome may partially be resolved in a select small group of patients by instituting a provocative intraarticular injection of a combination of a local anesthetic and a steroid. This approach enables one to determine whether the sacroiliac joint (SIJ) is the site of origin of the low back pain syndrome. We carried out a study of 71 computed tomography (CT)-guided injections in 58 patients with noninflammatory etiology. The injection was confirmatory to the SIJ abnormalities in 64 (90.1%) joints. The effect wore off in 2-14 days in 90% of the patients. We conclude that CT guidance is the best method of precise needle placement, and thus CT-guided anesthetic injection is the most specific confirmatory test for diagnosing the SIJ arthritis. In addition, in noninflammatory conditions, the role of intraarticular injection is primarily for diagnostic purposes and it has little or no therapeutic benefit.