Abstract Objective: To determine the clinical validity of provocative sacroiliac joint (SIJ) maneuvers in making the diagnosis of sacroiliac joint syndrome (SIJS). Design: Prospective constructive cohort study using sacroiliac joint block (SIJB) as the diagnostic gold standard. Setting: Tertiary care center. Patients: Consecutive patients describing low back pain including the region of the sacral sulcus. Physical examination revealed a positive response to three provocative SIJ maneuvers, two of which had to be Patrick's test and pain with palpation over the ipsilateral sacral sulcus. Interventions: All subjects underwent fluoroscopically guided SIJB. Main Outcome Measures: Response to SIJB was assessed with visual analog scale (VAS) ratings before and after the block. A reduction of the VAS rating by at least 80% was considered a positive response to SIJS. Results: Fifty consecutive patients met our criteria and underwent SIJB. Thirty patients had positive response to SIJB, making up the positive SIJS group. Twenty patients had less than 80% pain reduction with SIJB and thus comprised the negative SIJS group. The positive predictive value of provocative SIJ maneuvers in determining the presence of SIJS is therefore 60%. Conclusions: Our results do not support the use of provocative SIJ maneuvers to confirm a diagnosis of SIJS. Rather, these physical examination techniques can, at best, enter SIJS into the differential diagnosis.