Purpose: To present a series of rare and serious complications associated with endosseous implant therapy. Materials and methods: Five cases of mandibular osteomyelitis emerging in dental implant insertion sites are presented. In three cases, the clinical signs and symptoms of osteomyelitis occurred almost immediately following implant insertion. All cases occurred in patients with stable pre-existing medical conditions. Three of the patients were females and two were males, all of whom were in their sixth and seventh decades of life. Results: Clinical symptoms such as pain and local infection were observed in all cases, despite long-term antibiotic treatment. All cases underwent progressive surgical treatment including corticotomy, saucerization, sequestrectomy and drainage. Two cases exhibited spreading of bone infection in the mandible which required segmental mandibulectomy and fixation using reconstruction plates. The symptom-free state was only achieved following surgical intervention and antibiotic treatment in four patients. A minimal follow-up of 1 year revealed complete resolution of the infection and symptoms in four out of five patients. The outcome of the fifth patient is unknown. Conclusions: Osteomyelitis related to dental implants is a rare and serious complication. Prolonged antibiotics at high dosage together with aggressive surgical treatment is required. Increasing the awareness among dental surgeons and maintaining correct surgical principles are essential in order to reduce the risk of osteomyelitis. Keywords: dental implants, mandible, implant failure, osteomyelitis Conflict of interest statement: We have no conflict of interests to report.