Three hundred seventy-five patients with CIN on referral Pap and with a distinct cervical lesion on colposcopy were prospectively randomized to treatment with LLETZ or to standard colposcopic evaluation with directed cervical biopsies, endocervical curettage, and laser ablation of the transformation zone for biopsy proven CIN. Of the 195 patients that randomized to treatment with LLETZ, 32.5% had no evidence of dysplasia, 26.5% had CIN 1, 17.3% had CIN 2, 22.7% had CIN 3, and 0.5% had microinvasive carcinoma on final histologic evaluation. Of the 180 patients randomized to laser ablation, initial cervical biopsies demonstrated no evidence of dysplasia in 52.8% of patients, CIN 1 in 22.0%, CIN 2 in 18.3%, and CIN 3 in 5.7%. Only 114 (63.3%) of the women in the laser group required therapy. Complications were comparable for each treatment arm. Only 6.7% of patients randomized to LLETZ and 4.4% with laser ablation had persistent CIN on follow-up Pap. LLETZ appears to be effective, well tolerated, and less expensive, but the cost savings advantage of LLETZ over laser ablation may not apply to patients with CIN 1 on referral Pap smear since many do not require treatment.