purpose: to evaluate the detection of high oncogenic risk human papillomavirus dna (hpv-dna) immediately before and 4±1.25 months after large loop excision of the transformation zone (lletz) in the treatment of cervical intraepithelial neoplasia (cin). methods: in this clinical prospective study, 78 patients submitted to lletz from february to december 2001 were enrolled. all patients were submitted to colposcopic evaluation and had pap smear and hybrid capture ii (hc ii) specimens collected immediately before lletz and four months after the procedure. statistical analysis was made through odds ratio (or) calculations with 95% confidence interval (95% ci). results: before excision, 67 (86%) women had positive hc ii for high oncogenic risk hpv-dna, while four months afterwards only 22 (33%) maintained positive hc ii results. positive results of hpv-dna after treatment were not associated with previous viral load, compromised margins in the surgical specimen or age. four months after the procedure, detection of hpv-dna was significantly associated with cytological abnormalities (or = 4.8; ci 95%: 1.7-13.7) but not with histological residual disease or relapse (or = 6.0; ci 95%: 0.8-52.3). conclusion: hpv-dna detection was significantly reduced after treatment of cin, but was not associated with the presence of histologic residual disease or relapse.