Objective. Endoscopic mucosal ablation is a promising technique that is used to treat dysplastic Barrett’ s oesophagus. The purpose of this study was to investigate the efficacy and cost- effectiveness of two promising techniques, argon plasma coagulation (APC) and photodynamic therapy (PDT), in the ablation of dysplastic Barrett’ s oesophagus. Material and methods. Twenty- six patients with dysplastic Barrett’ s oesophagus (21 M, median age 60 years, median length 4 cm, 23 low- grade dysplasia (LGD), 3 high- grade dysplasia (HGD)) were randomized to APC: 13 patients, PDT: 13 patients. APC was performed at a power setting of 65 W and argon gas flow at 1.8 1/min in 1- 6 sessions (mean 5). PDT was performed 48 h after intravenous injection of Photofrin 2 mg/kg with a 630 nm red laser light, 200 J/cm through a PDT balloon in one session. All patients received treatment with high- dose proton pump inhibitors. Cost analysis was undertaken and the results were assessed by endoscopy and biopsies at 4 months and 12 months after therapy. Results. All patients in both groups showed a reduction in the length of Barrett’ s oesophagus. The median length of Barrett’ s oesophagus eradicated at the 4- month follow- up: APC 65% , PDT 57% and at the 12- month follow- up: APC 56% , PDT 60% . Dysplasia eradication at 4 months: APC 62% , PDT 77% , p = 0.03 (95% CI 0.66- 0.96) and at 12 months APC 67% , PDT 77% . Buried columnar glands with intestinal metaplasia were seen in both groups, with one patient in the PDT arm developing adenocarcioma under the neo- squamous epithelium. Severe adverse events included APC 2/13 (15% ) stricture, 1/13 (8% ) odynophagia, chest pain and fever; PDT 2/13 (15% ) photosensitivity, 2/13 (15% ) stricture. PDT would cost an additional ￡ 266 for every percentage reduction in Barrett’ s length and ￡ 146 per percentage reduction in dysplasia compared with APC treatment. Conclusions. APC and PDT are equally effective in eradicating Barrett’ s mucosa, with PDT being the more expensive treatment. However, PDT is more effective in eradicating dysplasia and the extra benefits of PDT are generated at an extra cost. The occurrence of buried columnar glands and carcinoma warrants caution. Long- term follow- up is needed to assess cancer prevention and the durability of the neo- squamous epitheliumto justify these interventions. Objective. This study was to investigate the efficacy and cost-effectiveness of two promising techniques, argon plasma coagulation (APC) and photodynamic therapy (PDT ), in the ablation of dysplastic Barrett’s oesophagus. Material and methods. Twenty-six patients with dysplastic Barrett’s oesophagus (21 M, median age 60 years, median length 4 cm, 23 low- grade dysplasia (LGD), 3 APC was performed at a power setting of 65 W and argon gas flow at 1.8 1 / min in 1- 6 sessions (mean 5). PDT was performed 48 h after intravenous injection of Photofrin 2 mg / kg with a 630 nm red laser light, 200 J / cm through a PDT balloon in one session. All patients received treatment with high- dose proton pump inhibitors. Cost analysis was undertaken was and the results were assessed by endoscopy and biops ies at 4 months and 12 months after therapy. Results. All patients in both groups showed a reduction in the length of Barrett’s oesophagus. The median length of Barrett’s oesophagus eradicated at the 4- month follow-up: APC 65% PDT 57% and at the 12- month follow-up: APC 56%, PDT 60% Dysplasia eradication at 4 months: APC 62%, PDT 77%, p = 0.03 (95% CI 0.66-0.66) and at 12 months APC 67%, PDT 77%. Buried columnar glands with intestinal metaplasia were seen in both groups, with one patient in the PDT arm developing adenocarcinoma under the neo- squamous epithelium. Severe adverse events included APC 2/13 (15%) stricture PDT 2/13 (15%) stricture. PDT would cost an additional £ 266 for every percentage reduction in Barrett’s length (1/8) odynophagia, chest pain and fever; PDT 2/13 and £ 146 per percentage reduction in dysplasia compared with APC treatment. Conclusions. APC and PDT are equally effective in eradicating Barrett’s mucosa, with P DT bHowever, PDT is more effective in eradicating dysplasia and the extra benefits of PDT are generated at an extra cost. The occurrence of buried columnar glands and carcinoma warrants caution. Long- term follow- up is needed to assess cancer prevention and the durability of the neo- squamous epitheliumto justify these interventions.