BackgroundBehçet’s Disease (BD) is a chronic auto-inflammatory, multisystem relapsing/remitting disorder of unknown aetiology. Oro-genital ulceration is a key feature of the disease and has a major impact on the patients’ quality of life. Other clinical manifestations include ocular inflammation, rheumatologic and skin involvement, while CNS and vascular complications can lead to considerable morbidity. The availability of a valid monitoring tool for BD activity is crucial in evaluating the impact of the disease on daily life activity. The aims of this study were to validate a novel tool for monitoring genital ulceration severity in BD and to assess the impact of genital ulcers on the Genital Health Quality of Life (GHQoL).MethodsGenital Ulcer Severity Score (GUSS) was developed using six genital ulcer characteristics: number, size, duration, ulcer-free period, pain and site. A total of 207 BD patients were examined, (137 females: mean age ± SD: 39.83 ± 13.42 and 70 males: mean age ± SD: 39.98 ± 11.95) from the multidisciplinary Behçet’s Centre of Excellence at Barts Health NHS Trust. GUSS was used in conjunction with Behçet’s Disease Current Activity Form (BDCAF).ResultsThe over-all score of GUSS showed a strong correlation with all genital ulcer characteristics, and the strongest correlation was with the pain domain (r = 0.936; P < 0.0001). Ulcer average size and ulcer pain were the major predicting factors in GUSS (β = 0.284; β = 0.275) respectively, and P-values were significant. Multivariate regression analysis indicated that the ulcer pain, size and site are the main ulcer characteristics having an influence on the GHQoL (R2: 0.600; P < 0.0001).ConclusionsThis study established the practicality of GUSS as a severity monitoring tool for BD genital ulcers and validated its use in 207 patients. Genital ulcers of BD have a considerable impact on the patients GHQoL.Electronic supplementary materialThe online version of this article (doi:10.1186/s13023-015-0341-7) contains supplementary material, which is available to authorized users.