In a study of 1000 women referred over 20 months with abnormal smears and in whom the entire transformation zone could be seen the aim was to test the feasibility of colposcopic assessment and treatment at one visit to the clinic. 897 women needed only one visit. This was achieved by using a modification of the large loop diathermy excision technique and by careful attention to the timing of the clinic visit. 103 required further visits, for the following reasons: incomplete excision on histology and/or subsequently abnormal smear (85), secondary haemorrhage (6), microinvasion or invasive carcinoma (9), biopsy specimens unusable (3). Further treatment was given in 4.1% of the cervical dysplasias. All patients treated in a single visit preferred this approach to the alternative of colposcopic assessment and biopsy followed, after histological examination, by local ablation by laser, excision by loop biopsy technique, or cone biopsy.