An accessory navicular bone (ANB) is present in 10-30% of normal feet. A morphological classification of ANB on the basis of the radiographic appearance distinguishes three types. Most symptomatic ANBs are of type 2. Although the diagnosis and treatment of sprained ankle are generally straightforward, together with an ANB, it might be misdiagnosed as a fracture. We present a 20-year-old male with type 2 ANB who was misdiagnosed as navicular fracture following sprained ankle. Turk J Phys Med Rehab 2011;57:172-4.