International Study Group for Behçet’s Disease Classification criteria
| Finding | Definition |
| Recurrent oral ulceration | Minor aphthous, major aphthous or herpetiform ulcers observed by the physician or reliably described by the patient which recurred at least three times over a 12-month period |
| Recurrent genital ulceration | Aphthous ulceration or scarring observed by the physician or reliably described by the patient |
| Eye lesions | Anterior or posterior uveitis or cells in the vitreous body on slit-lamp examination or retinal vasculitis detected by an ophthalmologist |
| Skin lesions | Erythema nodosum, pseudofolliculitis, papulopustular lesions or acneiform nodules not related to glucocorticoid treatment or adolescence |
| Positive pathergy test | Interpreted as positive by the physician at 24–48 hours |
A definite diagnosis requires recurrent oral ulceration with at least two of the other findings in the absence of other clinical explanations.