Background: Human immunodeficiency virus (HIV)- infected patients are more predisposed than HIV- negative women to develop squamous intraepithelial lesions (SIL) of the uterine cervix, and cervical dysplasia may be of higher grade in HIV- positive women than in HIV- negative subjects, with more extensive and multi-centric involvement of the lower genital tract by human papillomavirus (HPV)- associated lesions. Moreover, recurrence and progression rate of cervical intraepithelial neoplasia (CIN) is particularly higher in immunocompromised women. Design: Retrospective case-control study of HIV- positive women and HIV- negative controls, all affected by low-grade SIL of the uterine cervix, treated by loop excision or followed-up without treatment. Correlation of progression and recurrence of SIL with HIV status and CD4+ count. Patients: From September 1990 to October 1997, 75 HIV- positive low-grade-SIL patients, 47 treated and 28 followed-up without treatment, and 75 HIV- negative low-grade- SIL controls, 45 treated and 30 followed-up. Results: Among treated patients, 17/47 (36.2% ) HIV- positive and 5/45 (11.1% ) controls had recurrence (P < 0.0101, OR = 4.53, 95% CI = 1.5- 13.7), progression of untreated lesion was seen in 15/28 (53.6% ) HIV- positive and 7/30 (23% ) controls (P < 0.05, OR = 3.79, 95% CI = 1.23- 11.69). The risk of recurrence or progression of low-grade SIL linked to HIV seropositivity is about 4- 5 times higher in comparison with seronegative counterpart, matched for age, risk factors and lesion size. More significantly, considering the cut-off of 200 CD4+ /mm3 in HIV- positive women, 13/17 cases of recurrence (P < 0.05, OR = 4.88, 95% CI = 1.28- 18.58) and 10/15 cases with progression (P < 0.05, OR = 6.67, 95% CI = 1.24- 35.73) were immunocompromised (< 200 CD4+ /mm3), with a significant higher risk of recurrence or progression linked to immunodeficiency status. Considering time of progression or recurrence, during follow-up, Kaplan-Meier curves shows that HIV- positive status and immunodeficiency are correlated with more rapid evolution of cervical dysplasia and HPV- related lesions: comparison of recurrence in treated patients report P < 0.005 and progression in untreated P < 0.05 (Mantel-Haenszel log-rank test). Conclusions: Immunological status seems to be a determinant factor in prognosis of cervical SIL, HIV- positive women affected by this lesion, even if low-grade, need more aggressive management than the immunocompetent counterpart. Strict cytologic and colposcopic screening is recommended and CD4+ count and HPV- DNA testing may be useful risk indicators. Excisional procedures are preferred, while ablative treatments or wait and see policy may expose to some risk this type of population with poor compliance to follow-up. Background: Human immunodeficiency virus (HIV) - infected patients are more predisposed than HIV-negative women to develop squamous intraepithelial lesions (SIL) of the uterine cervix, and cervical dysplasia may be of higher grade in HIV- positive women than in HIV-negative subjects, with more extensive and multi-centric involvement of the lower genital tract by human papillomavirus (HPV) - associated lesions. Moreover, recurrence and progression rate of cervical intraepithelial neoplasia (CIN) is particularly higher in immunocompromised women. Design: Retrospective case- control study of HIV-positive women and HIV-negative controls, all affected by low-grade SIL of the uterine cervix, treated by loop excision or following-up without treatment. Correlation of progression and recurrence of SIL with HIV status and CD4 + count. Patients: From September 1990 to October 1997, 75 HIV-positive low-grade-SIL patients, 47 treated and 28 followed-up without treatment, and 75 HIV-negative low-gr Results: Among treated patients, 17/47 (36.2%) HIV-positive and 5/45 (11.1%) controls had recurrence (P <0.0101, OR = 4.53, 95 % CI = 1.5-13.7), progression of untreated lesion was seen in 15/28 (53.6%) of HIV-positive and 7/30 (23%) controls (P <0.05, OR = 3.79, 95% CI = 1.23-11.69 ) The risk of recurrence or progression of low-grade SIL linked to HIV seropositivity is about 4- 5 times higher in comparison with seronegative counterpart, matched for age, risk factors and lesion size. CD4 + / mm3 in HIV-positive women, 13/17 cases of recurrence (P 0.05, OR = 4.88, 95% CI 1.28-18.58) and 10/15 cases with progression CI = 1.24-35.73) were immunocompromised (<200 CD4 + / mm3), with a significant higher risk of recurrence or progression linked to immunodeficiency status. Considering time of progression or recurrence, during follow-up, Kaplan-Meier curves shows that HIV- positive status and immunodeficiency are correlated with more rapid evolution of cervical dysplasia and HPV-related lesions: comparison of recurrence in treated patients report P <0.005 and progression in untreated P <0.05 (Mantel-Haenszel log-rank test). Conclusions: Immunological status seems to be a determinant factor in prognosis of cervical SIL, HIV-positive women affected by this lesion, even if low-grade, need more aggressive management than the immunocompetent counterpart. Strict cytologic and colposcopic screening is recommended and CD4 + count Excisional procedures are preferred, while ablative treatments or wait and see policy may expose to some risk this type of population with poor compliance to follow-up.