Background In Senegal, an epidemiological survey conducted in 2004 among 463 men having sex with men (MSM) revealed a high HIV prevalence (21.5%) and high proportions of unprotected sex and bisexual activity (Wade, 2005). The health authorities concluded that not giving MSM access to health care could compromise all the efforts achieved in Senegal in combating HIV. Consecutively, interventions targeting MSM were developped, aiming to improve their access to health care programs and to raise their awareness to sexual risk. A second survey carried out in 2007 measured the evolution of HIV and STIs prevalence among MSM and assessed the impact of these preventive operations. Methods In the capital city and in two medium-sized towns, 501 MSM recruited through the snowball referral method were surveyed in 2007 with a face-to-face close-ended standardized questionnaire. They provided blood and urine samples to be tested for STIs and HIV. The biological and behavioral indicators were compared to those collected in 2004. Results The HIV prevalence among MSM remains stable, from 21.5% [95% CI : 17.8-25.7] in 2004 to 21.8% [95%CI :18.3-25.7] in 2007 (p=0.9), but risk behaviors decreased meanwhile. The proportion of men who had at least one unprotected insertive anal intercourse during the last month with a male partner decreased from 24% to 9% (p<0.01), the proportion of men who had at least one unprotected receptive anal intercourse decreased from 21% to 10% (p<0.01), and the proportion of men who had at least one unprotected intercourse with a female partner decreased from 18% to 12 % (p<0.01). Conclusion Prevention interventions targeted towards men having sex with men led to a reduction of risk behaviors in this group, showing their efficiency. They should be systematically implemented in this high-risk group.