中文摘要：

目的了解北京市男男性行为者无保护性同性性行为情况及其影响因素。方法2006年11月～2007年2月，在北京市朝阳区对男男性行为者进行问卷调查，内容包括社会人口学、近3个月行为学特征等。结果在所调查的541名男男性行为者中，分别有49．5％（268／541）和36．6％（198／541）的调查对象在过去的1个月与固定和临时男性发生过肛交。多因素Logistic回归分析结果显示，近3个月结婚／与女朋友同居（OR=3．00；95％CI1．40～6．40）更容易与固定男性近1个月发生无保护性肛交，近1个月感觉到孤独（OR=0．47；95％CI0．28～0．78）较少与固定男性性伴近1个月发生无保护性肛交；近3个月通过浴池／厕所／公园寻找男性性伴（OR=2．01；95％CI1．07～3．79）、近3个月未参加过艾滋病项目（OR=2．84；95％CI1．01～7．98）更容易与临时男性性伴近1个月发生无保护性肛交。结论男男性行为者中无保护性肛交行为普遍存在，应加强对这个人群的行为干预以降低其危险行为。

英文摘要：

Objective To investigate the risk factors associated with unprotected anal sex among men who have sex with men （ MSM ） in Beijing. Methods From November 2006 to February 2007, MSM were investigated in Chaoyang district. Results Among 541 MSM investigated, 49. 5% （268/541） and 36. 6% （ 198/541 ） had had anal sex with steady and casual partners in the past month respectively. Multivariate Logistic regression model demonstrated that MSM who had been married or were cohabitating with girlfriends in the past 3 months （ OR = 3.00 ; 95% CI 1.40 - 6.40） were more likely to have unprotected anal sex with steady partners in the past month. MSM who felt loneliness in the past month （OR = 0. 47; 95% CI 0. 28-0. 78）was less likely to have unprotected anal sex with steady partners in the past month; MSM who sought for male partners in bathrooms/toilets/parks in the past 3 months （OR =2.01 ; 95% CI 1.07 -3.79）, hadn＇t participated in HIV items in the past 3 months （OR =2.84; 95% CI 1.01 -7. 98） were more likely to have unprotected anal intercourse with casual partners in the past month. Coneluslon The phenomenon of unprotected anal sex among MSM is prevalent, behavioral intervention should be strengthened to decrease the risk behaviors.