Necrotizing ulcerative gingivitis (NUG) can be a painful periodontal disease that can lead to loss of the interdental papillae. It is usually accompanied by systemic signs of fever, malaise and cervical and submandibular lymphadenopathy. It is caused by the profileration of anaerobic bacteria and has been linked to smoking and immunosuppression. This case series reports the occurrence of NUG in orthodontic patients and demonstrates that there is a varying scale of severity of the condition. Orthodontists should be aware of the clinical signs of NUG to ensure early detection and treatment of their patients in order to prevent irreversible loss of the interdental papillae and reduce the likelihood of recurrence. A treatment regime is suggested.