Acquired Immuno Deficiency Syndrome (AIDS) has become the current major public healthrnproblem in the developed and developing countries. The epidemic is one of the greatestrnchallenges ever to Global well-being.rnThis study was designed and conducted with the aim of assessing risky sexual behavior for HIVrninfection spreading with special focus on the night markets and mobile people.rnA multistage, cross-sectional survey and qualitative study was carried out between Novemberrn2003 and January 2004 in Gummer woreda, Gurage zone.rnA total of 838 respondents participated in the survey part and in the qualitative four FGDs ofrndifferent key informants and 14 individual in-depth interviewees were enrolled and participatedrnin this study. The result showed that 43 (19.2%) of males and 5 (1.8%) of females ever hadrnextramarital sex .Females were being protective with [OR= 0.05, 95% CI: 0.01, 0.23]. Amongrnthe age group of 15-54years, 36 (18.2%) of 35-54 years and 25 (12.0%) of age 15-34 years hadrnengaged in risky sexual behaviors in relationship to night markets. Regarding marital status,rn50(10.0%) of married and 11 (3.3%) of not currently married had engaged in risky sexual inrnrelationship to night markets. Among the married respondents, 26 (10. 8%) of males and onernfemale had their first sexual contact with non-regular partners. Regarding occupation, 17 (6.6%)rnof farmers and 44 (7.6%) of others occupation (students, wives, traders and jobless) had engagedrnin risky sexual behaviors in relationship to night markets. Other occupation had 2.5 times morernengaged in risky sexual behaviors than farmers with [OR= 2.5, 95%CI: 1.07, 5.90]. Among thernrespondents only 27 (3.2%) had reported frequently use of condom in the last six months duringrnviiirnpremarital and extramarital sex. Almost all, 826 (98.6%) have heard about HIV/AIDS. Eightrnhundred and twenty six (98.4%) reported that HIV/AIDS is transmitted by unprotected sex.rnMost of the FGDs discussants and individual in-depth interviewees said that nowadays nightrnmarkets have become a source for HIV/AIDS transmission in the area.rnMost of the respondents did not think that they were at risk of acquiring HIV infection whilernthey were at risk in relation ship to night markets and mobility. It needs urgent measure intermsrnof HIV prevention and control in the study area.