In a randomized study, 204 patients with exocervical intra-epithelial neoplasia were allocated to either laser evaporation (103) or cryocoagulation (101). The patients were treated on an outpatient basis without anesthesia. In the case of initial treatment failure the same method was to be used for retreatment. One hundred and eighty-seven patients were followed-up for an average of 50 months (12-80). Eighty-six of 94 laser-evaporated patients (91%) and 89 of 93 cryocoagulated patients (96%) were cured after one treatment. Five of 8 laser failures and 3 of 4 cryo failures were cured by retreatment. The cure rate after one or two laser evaporations was 97% (91 of 94 patients), and after one or two cryo coagulations, 99% (92 of 93 patients). Eighty per cent of residual or recurrent neoplasia occurred within 15 months and 96% within 2 years of treatment. No invasive neoplasia occurred during the follow-up period and no tendency was seen towards higher grades of intra-epithelial neoplasia in the failures compared with the initial diagnoses. It is concluded that laser evaporation and cryocoagulation are equally effective for the treatment of exocervical intra-epithelial neoplasia.