Wei F, et al. - Among 2,302 heterosexual men and 2,371 heterosexual women aged 18-55 years old in Liuzhou, China, gender-based disparities in the natural history of anal human papillomavirus (HPV) infection were explored. Researchers obtained perianal/anal canal (PA) swab samples semiannually from the participants. Using PCR, they genotyped specimens for HPV DNA. Using Poisson regression, they assessed sex differences of incidence and clearance by estimating incidence rate ratio (IRR) and clearance rate ratio (CRR), respectively. The estimated IRR was 0.39. For men vs women, incidences of PA oncogenic HPV were 3.4 per 1,000 person-months and 8.6 per 1,000 person-months, respectively, and CRR was 1.54. Among women, a higher burden of anal cancer vs men could be seen on account of higher incidence and slower clearance of anal carcinogenic HPV infection among women in this heterosexual population.