Over the past twenty years, the placement of oral implants has become a routine procedure in the reconstruction of fully or partially edentulous patients. As implants are becoming more popular, their number is increasing, especially the number of implants in the jaw. Still, as the number of implants grows, so does the number of adverse complications. Peri-implant diseases are one of the most common biological complications of the implant therapy. Periimplant mucositis is the inflammation limited to the mucosa around the implant, while periimplantitis represents an advanced stage, with affection and loss of the supportive bone. Periimplant diseases are most often caused by the bacterial contamination. The treatment needs to primarily be antimicrobial, i.e. to suppress the opportunistic pathogens and create local environments and conditions of microflora present in the healthy tissue. The therapy of periimplant infections can be categorized as nonsurgical and surgical approach. Nonsurgical approach has shown to be effective in the treatment of mucositis, but doesn’t give as satisfying results in the treatment of periimplantitis. The aim of the surgical therapy is to obtain the direct access for cleaning and decontamination of the implant surface, as well as to manage progressive bone loss, and despite the bone loss, fill the bone defect and gain reoseointegration. Surgical techniques can be divided into resective and regenerative approach. Periimplant therapy has not been completely perfected, and more clinical research is needed to find an ideal, unique protocol which guarantees the success of the treatment. The long term success of the treatment equally depends on the knowledge and skills of the therapist as well as the motivation of the patient to maintain immaculate oral hygiene and to regularly schedule check-up.