Abstract: ObjectiveTo explore the characteristics of digit ratio (D) among the men who have sex with men (MSM) exhibiting different sex role in homosexual activity in Kunming city.MethodsTotally 115 MSM with different self-reported sex role (47 insertive,37 receptive,and 31 both insertive and receptive) were recruited among the attendances of Caiyun Tiankong Health Counseling Service Center of Kunming City (an institution for human immunodeficiency virusHIVvoluntary counseling and testing) during December 2014 and April 2015;115 age- and nationality-matched controls were recruited among healthy physical examinees in a medical institution during the same period.The length of 2nd to 5th fingers of both hands were measured and D values (2D:3D,2D:4D,2D:5D,3D:4D,3D:5D,and 4D:5D) were calculated for all the participants.ResultsThe mean D values among the MSM distributed in a decreased sequence of 2D:3D,2D:4D,3D:4D,2D:5D,4D:5D,and 3D:5D.The mean D values of 2D:4D and 2D:5D of right hand were higher among the MSM than those among the controls (0.957 7±0.048 1 vs.0.941 4±0.038 and 1.229 8±0.083 4 vs.1.204 1±0.069 5;P=0.005 and P=0.012).The D value of 2D:4D of right hand differed by the sex role among the MSM;the values for the MSM reporting different sex role distributed in a decreased order of receptive role,inserter role,and both roles.ConclusionDigit ratio could be used as a biomarker for the MSM in Kunming.