Introduction: Sesamoids are ovoid bones with variable size and shape in the course of tendons, can be found in different parts of skeletal system.
Case presentation: We report a case of 61-year-old woman in whom we observed a large accessory bone located in the anterior aspect of the left ankle joint. Since such accessory bones are found very infrequently, their presence may cause some diagnostic confusion.
Conclusion: Regarding complaints in foot area one has to be familiar with such bones in order to make a correct diagnosis.