Abstract: Introduction: Oral aphthosis (OA) is seen in 96% of patient with Behcet’s Disease (BB) OA is said to be rather frequent in the general population. It was therefore interesting to determine whether OA in the general population had also a genetic background as it is for BD. It was also interesting to determine if the genetic background was similar in both conditions (BD and OA in the general population). Therefore, it was necessary to find: 1- The incidence of OA in the general population and in their first-degree relatives. 2- The ethnic distribution of individuals with OA and without OA in the general population. 3- The incidence of familial OA in BD patients. 4- The ethnic distribution in BD patients. Materials and Methods: From a general dermatology setting, 1365 persons were selected consecutively. They were evaluated for the presence of OA in themselves and in their first-degree relative (father, mother, brother, sister, or children). Their ethnic origin was also determined. The same study was done on 1260 consecutive BD patients. Results were compared by the chi square test (X 2). A confidence interval (CI) at 95% was calculated for the percentages. Results: In a cohrt of 3740 BD patients, 96.1% (CI: 0.6) had OA. In the series of 1260 BD patients OA was present in 96.7% (CI:1.1). In this series, 615 patients (48.8%, CI: 2.8) had a familial history of OA. Among them, 548 patients (43.5%, CI: 2.7) had OA in their first-degree relatives. Turks were 2.1 times more involved than Caucasians. In the General Population, 282 patients (20.7%, CI: 2.2) had OA. From those who had OA, 167 (59.2%, CI: 5.7) had OA in their first-degree relatives. The occurrence of OA in the first-degree relatives in the general population was more frequent than in BD patients. The difference was statistically significant (X 2: 18.683, p<0.0001). Turks were 1.3 times more involved than Caucasians. Comparison of the BD group with the general population showed that Turks were more involved in the BD group than in the general population. The difference was statistically significant (X 2: 9.645, I P<0.002) Discussion: OA was 2.9 times more frequent in the first-degree relatives of non BD OA patients than in the general population. This is in favor of a genetic factor. The frequency of ethnic groups was the same among OA and non-OA individuals. In BD on the contrary. Turks were 2.1 times more involved than Caucasians. This shows that the genetic factor is not the same for the two conditions. We therefore conclude that despite the same clinical picture. OA is not the same in the 2 conditions.