S Stomatits aphtosa is the most common of oral lesions that can be suffered by men or women in some populations. This lesion can occur in any pert of oral mucosa and usually found in noIcreatinine mucosa. The objective of this research was to develop the most vulnerable location of aphthous stomatitis which was carried out in RSOM (P) Usakti Jakarta 2004-2008.Method: The research is a descriptive study using frequency distribution table. Processing data using SPSS program version 16. There were 543 subjects observed, composition of 133 men and 407 women.Resuhs : From this research, we found that there were five co1111mn locations of aphthous stomatitis with a percentage of 54.3% for lip mucosa! , 15. cbecck mucosal, 12.2% for tongue, 4.2% oral base, and 2% for gingiva. The top five predisposing factors found were trauma (35.3%), food (31,JG/4), psychological (19.6%), hormonal (8.7%), and genes (4.8%).Conclusion: By maintaining good oral hygiene and avoiding the predisposing factors, hopefullywe can reduce the incidence and recurrence of aphthous stomatitis.Keywords: aphthous stomatitis, predilecion, predisposition