PURPOSE: This study was designed to analyze the usefulness of Single Photon Emission Computed Tomography/Computed Tomography (SPECT/CT) in diagnosing symptomatic accessory tarsal bones. MATERIALS AND METHODS: Twenty four feet (16 patients) with symptomatic accessory navicular and/or os trigonum, who agreed to take SPECT/CT, were included in this study. Fifteen feet had accessory navicular, five had os trigonum, and four had both. According to the uptake in the SPECT/CT, 11 feet were classified into high and 13 into low uptake groups. The low uptake group was treated non-operatively, while the high uptake group received operations when initial conservative management failed. A modified Kidner procedure was performed for accessory navicular and arthroscopic excision was done for os trigonum. After a mean follow-up of 6.8 (range, 3~13) months, the American Orthopaedic Foot and Ankle Society (AOFAS) score and the Visual Analogue Scale (VAS) for pain were compared. RESULTS: Patients in the high uptake group had a higher initial mean VAS score (7.0+/-0.8 vs 2.2+/-0.9, p<0.05) and a lower initial mean AOFAS score (45.9+/-9.2 vs 83.9+/-4.2, p<0.05) compared to the low uptake group. All patients in the low uptake group improved after non-operative treatment. Seven patients underwent operations and had a decreased VAS (1.6+/-0.5) and an increased AOFAS score (88.3+/-1.8) at the last follow-up. Four patients in the high uptake group demonstrated erratic symptoms. CONCLUSION: SPECT/CT can be a useful diagnostic tool and helpful in designing treatment plans for symptomatic accessory navicular and os trigonum.