Information about vulvovaginal and perianal condylomata acuminata and intraepithelial neoplasia in women infected with HIV-1 is needed to develop guidelines for clinical care. Our aim was to investigate the incidence of these lesions in HIV-1-positive and HIV-1-negative women and to examine risk factors for disease. In a prospective cohort study, 925 women had a gynaecological examination twice yearly—including colposcopy and tests for human papillomavirus DNA in cervicovaginal lavage—for a median follow-up of 3·2 years (IQR 0·98–4·87). Vulvovaginal and perianal condylomata acuminata or intraepithelial neoplasia were present in 30 (6%) of 481 HIV-1-positive and four (1%) of 437 HIV-1-negative women (p<0·0001) at enrolment. Women without lesions at enrolment were included in an incidence analysis. 33 (9%) of 385 HIV-1-positive and two (1%) of 341 HIV-1-negative women developed vulvovaginal or perianal lesions, resulting in an incidence of 2·6 and 0·16 cases per 100 person-years, respectively (relative risk 16, 95% CI 12·9–20·5; p<0·0001). Risk factors for incident lesions included HIV-1 infection (p=0·013), human papillomavirus infection (p=0·0013), lower CD4 T lymphocyte count (p=0·0395), and history of frequent injection of drugs (p=0·0199). Our results suggest that HIV-1-positive women are at increased risk of development of invasive vulvar carcinoma. Thus, we recommend that, as part of every gynaecological examination, HIV-1-positive women should have a thorough inspection of the vulva and perianal region, and women with abnormalities—except for typical, exophytic condylomata acuminata—should undergo colposcopy and biopsy.