Analyse long term (20 years) cytology and histology outcomes following treatment of high grade cervical intraepithelial neoplasia (HGCIN) with Cold Coagulation (CC).     Methods   All women having CC for HGCIN between Jan 1996 and December 1998 (36 months; n=885) were identified; data was collected on age of patients, symptoms, colposcopy findings and biopsy reports. Local and national (cytology and colposcopy) databases and colposcopy records were used to collect long term follow up data. Probability of CIN recurrence was assessed using Kaplan Meir ‘Survival’ curve.     Results  Follow up data (available for 796) was collected in 2018 capturing 20 years of follow-up data. 281 women were treated for CIN2 and 515 women for CIN3. 791/796(>99%) were treated at first visit and 152/796(19%) had symptoms at presentation. 262/796(33%) had evidence of glandular involvement on pre-treatment biopsy. Probability of having consistently normal cytological follow up was 92%, 89%, 86% and 83% at 5, 10, 15 and 20 years respectively. Cumulative probability of having recurrent HGCIN was 0.5% at 5 years, 1% at 10years, 1.9% at 15 years and 3% at 18 years.      Conclusion  CC is a safe and effective treatment for HGCIN which is now shown to have stood the test of time. We advise more widespread adoption in the UK and globally so long as agreed criteria are met.