BACKGROUND Sesamoid bones and accessory ossicles of the foot and ankle, although mostly asymptomatic, can be sources of pain or degenerative changes in response to overuse and trauma. We investigated the prevalence of accessory ossicles and sesamoid bones in a population of Italian women with hallux valgus. METHODS A single-center study was performed to determine the prevalence of accessory ossicles and sesamoid bones in the ankle and foot. A total of 505 women with hallux valgus aged 26 to 80 years at the time of hallux valgus correction were examined. Anteroposterior, oblique, lateral foot radiographs and a Muller view were examined regarding the presence, prevalence, coexistence, and distribution of accessory ossicles and sesamoid bones in both feet. The radiographs were analyzed independently by three experienced specialists in foot and ankle surgery. Disagreements were discussed in a consensus meeting, where the radiographs were reevaluated and a final decision was made. RESULTS There was no statistically significant difference between data of the accessory ossicles and sesamoid bones according to the χ(2) test. Sesamoid bones were detected in 404 of the 505 patients. The fifth metatarsal sesamoid bone was found in 97 patients. All of the patients presented hallucal sesamoid bones. CONCLUSIONS This is the first detailed report of the prevalence of accessory ossicles and sesamoid bones of the feet in Italian women with hallux valgus. These findings could help clinicians in the diagnosis and management of disorders of accessory ossicles and sesamoid bones, which are often undiagnosed, painful foot syndromes.