Objectives: This study aims to document a detailed investigation on thesesamoid bones (SBs) of Turkish subjects from different parts of Turkeyin a multi-center study, in both hands, according to gender, frequencyand divisions of the bones’ coexistence and bilaterality by radiography.Patients and methods: This retrospective and three-centered studywas performed between June 2010 and April 2012. Sesamoid boneswere examined by anteroposterior and oblique X-rays of 1,444 handsof 772 subjects (367 males, 405 females; mean age 42.7 years;range, 18 to 87 years). All X-rays were evaluated by at least twoindependent observers. In controversial circumstances, at least threeobservers together gave the final decision by consensus.Results: Metacarpophalengeal (MCP) joint of the thumb (MCP 1)had sesamoid in all subjects (100%) and it was seen bilaterally.The prevalence of the SB was 42.8% in the second MCP joint(MCP 2) in 772 subjects and 36.6% in 1,444 hands, 1.6% in thethird MCP joint (MCP 3) for the subjects and 1.1% for the hands,0.1% in the fourth MCP joint (MCP 4) for the subjects and 0.1%for the hands, and 72.5% in the fifth MCP joint (MCP 5) for thesubjects and 62.5% for the hands. The prevalence of SB in thefirst interphalangeal joint (IP 1) was 21.8% and SB was detectedin 18.6% of the hands. Sesamoid bones of the MCP 2, MCP 5,and IP 1 was recorded more frequently in females. Sesamoid boneof the same joints (MCP 2, MCP 5 and IP 1) was detected morefrequently bilaterally than unilateral right side and more frequentlyunilaterally on right side than unilateral left side.Conclusion: The distribution of SBs varies according to handregions, gender, and side. Having knowledge of the locations and therate of bilaterality of SBs may assist clinicians in both clinical andradiological diagnoses.