Infection with oncogenic types of human papillomavirus (HPV) is the main causal factor of cervical cancer and its precursor lesion (cervical intraepithelial neoplasia [CIN]). Cellular immunity may be critical in the elimination of HPV-harboring cells. Interleukin-10, a T-helper type 2 cytokine, has a suppressive effect on cell-mediated immunity. Resistance to apoptosis through the Fas pathway might enable many cancers to escape the immune system. We examined in a large study population whether three polymorphisms in the IL-10 gene and a polymorphism at position -670 of the Fas promotor affect susceptibility for cervical cancer or its precursor. In addition, it was studied whether these polymorphisms were causal and not merely associated by typing microsatellite markers in the region surrounding both genes. A total of 311 CIN, 695 cervical cancer patients, and 115 family-based and 586 unrelated controls were analyzed. Association analysis revealed an increased CIN (II-III) (OR 1.44 [1.06-1.97]) and squamous cell carcinoma of the cervix (OR 1.35 [1.04-1.75]) for individuals heterozygous for the A-allele of the IL-10-592 polymorphism. In contrast to previous findings, no association was found for the IL-10-1082 polymorphism. While an increased risk for adenocarcinoma (AC) in heterozygotes (OR 1.59 [1.02-2.48]) was observed. Our study shows a possible role for the IL-10 gene in CIN and squamous cell cervical cancer susceptibility in the Caucasian population; simultaneously, there might be a role for the Fas gene in the development of AC of the cervix. Further investigations with a higher density of markers are necessary to find the causal mutation.