It has been proposed that women who have a negative colposcopic examination or who have no cervical intraepithelial neoplasia (CIN) on colposcopic biopsy can be safely returned to routine screening with the next visit being three or five years later. We present data regarding 551 women who had colposcopy in Wales for a low-grade cytological abnormality and who were followed through Cervical Screening Wales for subsequent CIN. Of 436 women declared CIN free initially, 26 (6.0%) had high-grade CIN diagnosed on follow-up. We suggest that additional screening at an interval of less than three years should be offered to women with a negative colposcopy or a biopsy without CIN.