Human immunodeficiency virus (HIV) seroadaptive behaviors, such as serosorting and strategic positioning, are being increasingly practised by homosexual men; however, their impact on sexually transmissible infections is unclear.Participants were 1427 initially HIV-negative men enrolled from 2001 to 2004 and followed to June 2007. Participants were tested annually for anal and urethral gonorrhoea and chlamydia, herpes simplex virus, and syphilis. In addition, they reported diagnoses of these conditions, and of genital and anal warts between annual visits, and sexual risk behaviors.Compared with men who reported no unprotected anal intercourse (UAI), serosorting was associated with an increased risk of urethral (incidence: 6.06 vs. 3.56 per 100 person-years (PY), hazard ratio (HR) = 1.97, 95% confidence interval [CI]: 1.43-2.72) and anal (incidence 3.95 vs. 2.80 per 100 PY, HR = 1.62, 95% CI: 1.11-2.36) chlamydia. Compared with men who reported UAI with HIV nonconcordant partners, men who practised serosorting had significantly lower risk of incident syphilis (incidence 0.18 vs. 1.00 per 100 PY, HR = 0.21, 95% CI: 0.05-0.81) and urethral gonorrhoea (incidence 2.15 vs. 5.52 per 100 PY, HR = 0.61, 95% CI: 0.39-0.96). Compared with men who reported no UAI, strategic positioning was associated with an increased risk of urethral gonorrhoea (incidence 4.11 vs. 2.10 per 100 PY, HR = 1.72, 95% CI: 1.05-2.83) and chlamydia (incidence 8.71 vs. 3.56 per 100 PY, HR = 2.22, 95% CI: 1.55-3.18). Compared with men who reported receptive UAI, the incidence of anal gonorrhoea (incidence 1.48 vs. 3.83 per 100 PY, HR = 0.38, 0.20-0.74) and chlamydia (incidence 3.10 vs. 6.30 per 100 PY, HR = 0.44, 95% CI: 0.27-0.69) was significantly lower in those who practised strategic positioning.For men who reported seroadaptive behaviors, rates of some bacterial sexually transmissible infections were higher than in men who reported no UAI. However, rates were lower than for men who reported higher HIV risk behaviors.