This paper reports the treatment of prepubertal periodontitis in a 3-year-old girl with Papillon-Lefèvre Syndrome. Initially, the patient was found to have a myeloperoxidase deficiency and microbiological tests have identified Bacteroides and Fusobacterium, in 60% and 25%, respectively of the total number of microbial flora cultivated. The initial treatment was extraction of all the primary teeth with grade 3 mobility, scaling, root planing and daily subgingival irrigation with a 0.2% solution of chlorhexidine. Several months before the eruption of the first permanent molars, the rest of the primary teeth were extracted. The patient was treated with daily subgingival irrigation of chlorhexidine and weekly professional oral hygiene. At the age 6 1/2 years, the permanent teeth have normal gingiva and crevice depths; microbiological investigation reveals a prevalence of the coccoid forms, and radiographs show no evidence of periodontal pathology.