Aim: To investigate the indication of systemic antimicrobial agents used by dental professionals for treatment of patients affected by periodontal diseases. Methods: Interviews by a questionnaire were held with 225 professionals of different dental specialties and who performed periodontal treatment. Results: Among interviewees, 94% indicated systemic antibiotics as a form of periodontal disease treatment. Their main indication was for periodontal abscesses (80%) followed by aggressive periodontitis (62%) and necrotizing diseases (45%). The most frequently used antibiotics were amoxicillin (81%) and metronidazole (57%). The medications were indicated in association with mechanical therapy by 67% of the professionals. As regards the occasion of indication, 60% indicated systemic antibiotic therapy before and after mechanical periodontal scaling and root planing. Seventy-eight percent of the professionals indicated antibiotics associated with periodontal surgery for access to scaling, and 76% indicated it before and after the surgical procedure. Among the interviewees, 99% took into account systemic involvement for drug administration. Conclusions: It was concluded that a considerable portion of professionals indicate systemic antibiotic-therapy in an incoherent manner and in situations in which there is no indication for antibiotic use, or with ineffective protocols.