Background:Unprotected anal intercourse (UAI) has previously been associated with human immunodeficiency virus (HIV) infection.Male students who have sex with men (SMSM) are at increased exposure to experience UAI.The aim of this study was to investigate the status of UAI and related factors among SMSM in three north regions of China.Methods:From November 2018 to January 2019,SMSM,18 years or older,studying or living in Beijing,Tianjin,or Shijiazhuang,who had anal sex in the past 6 months were recruited by community-based organizations to participate in an unmatched,casecontrol study.Detailed demographic and behavioral information were collected via self-administrated electronic questionnaires and factors related to UAI were assessed using uni-and multivariate logistic regression analyses.Results:Among the 511 SMSM included in the study,210 (41.1％) reported UAI in the past 6 months.SMSM who had sexual partners at least 10 years older than themselves (odds ratio [OR] =2.277,95％ confidence interval [CI]:1.380-3.756),used vacant capsules before sexual activity (OR =3.858,95 ％ CI:1.472-10.106),had a self-perceived moderate-HIV risk (OR =2.128,95 ％CI:1.403-3.227),and unprotected,first anal intercourse (OR =2.236,95 ％ CI:1.506-3.320) had increased odds of UAI.Contusions:Factors associated with increased odds of engaging in UAI in the past 6 months among SMSM included having older sexual partners,using vacant capsules,having a self-perceived moderate risk of HIV,and unprotected,first anal intercourse.Continuing education on risk reduction,including improving condom decision making in age-discordant relationships could help address the sexual risk behaviors among SMSM.