The aim of this case report was to discuss a possible relation between Ulcerative Colitis (CU) and Localized Aggressive Periodontitis. A 39-year-old female patient suffering from CU was referred to the Section of Periodontology of the University Dental Clinic Heidelberg in August 2000. The patient reported that, in the past, CU bursts were always preceded by acute episodes of oral inflammation. Clinical examination revealed pocket depths (PD) between 2 and 11 mm, furcation involvement (FK) up to class III, and increased tooth mobility. Microbiological sampling revealed elevated numbers of subgingival B. forsythus and P. gingivalis. Since November 15th 2000 the patient was hospitalized due to recurring fever and abdominal pain (clinical diagnosis: acute CU burst, histologically confirmed by biopsy). No pathogen bacteria could be traced in the stool. In spite of systemic ciprofloxacin (intercurring urogenital infection) and prednisolon, fever bursts persisted. After other possible causes had been excluded, the patient was referred for dental examination and therapy to the Section of Periodontology. On December 5th and 6th the teeth 2, 15, and 31 (class III FK, PD 7-11 mm) were extracted and all remaining teeth subgingivally instrumented with adjunctive systemic antibiotics (Loracarbef/Metronidazol) according to the concept of 'full-mouth-disinfection' [Quirynen et al. 1995]. The fever disappeared and two days later, the patient was dismissed from hospital. One month later, PD were reduced to 2-5 mm (tooth 13: 7 mm). No bleeding on probing was recorded. Presumably, there is a relation between Aggressive Periodontitis and CU bursts. If there are further hints for associations, case control and longitudinal studies may provide further evidence. Keywords: colitis ulcerosa, Lokalisierte aggressive Parodontitis