Abstract: From 1969 to 1993 six major sets of diagnosis criteria were proposed for BD. The analysis of sensitivity, specificity and the accuracy was done on 2632 BD patients and 1916 control patients. A Confidence Interval (CI) at 95% was calculated for each result. Sensitivity: Mason & Barnes 70.9% ± 1.7, O'Duffy 77% ± 1.6, International 84.5% ± 1.4, Dilsen 89.4% + 1.2, Japan 90.8% ± 1.1, Iran 95.6 ± 0.8 (traditional format) and 97.1 ± 0.6 (classification tree). Specificity: Dilsen 90.2% ± 1.3, Iran 95% ± 1 (traditional format) and 95.9% ± 0.9 (classification tree), Japan 96.6% ± 0.8, International 97.9% ± 0.6, O'Duffy 97.9% ± 0.6, and the Mason & Barnes criteria 99.5% ± 0.3. Accuracy: Mason & Barnes 83% ± 1.1, O'Duffy 85.8% ± 1, Dilsen 89.7% ± 0.9, International 90.1%.± 0.9, Japan 93.3% ± 0.7, and for Iran criteria 95.4 ± 0.6 (traditional format) and 96.6 ± 0.5 (classification tree). The most complete and accurate system for calculating a disease activity index is actually the IBDDAM. The scoring system is as follow. For each attack: 1 point for each of the followings: Oral aphthosis (2 points if more than 5 ulcers), genital aphthosis (1 paint for each lesion), pseudofolliculitis (2 points if more than 10), erythema nodosum (2 points if more than 5), arthralgia, cephalea, superficial phlebitis, pathergy phenomenon. 2 points for mono-arthritis, phlebitis (each vessel), epididymitis. 3 points for oligo/poly arthritis, mild CNS involvement, mild intestinal manifestations. 6 points for large vessel thrombosis, moderate to severe CNS manifestations, moderate to severe Intestinal manifestations. All points of each attack are added together to get the total. The total is divided by the number of months during which the calculation was done. The result is a Mean Disease Activity Index per Month. For the eye: 1 to 4 points for each of the following inflammatory manifestations: Flare, cell, KP, and hypopion in anterior chamber. Cell, snow ball, and snow banking in posterior chamber. Periarteitis, periphlebitis, retinal edema, and retinitis for retina. Edema and papillitis for the disc. Edema for macula.