Purpose: The aim of this review is to describe the current guidelines for the differential diagnosis of periimplant diseases. Materials and Methods: Synopsis reviews were conducted to define the differential diagnosis of periimplant disease through an electronic literature search in MEDLINE up to February 2018. Discussion: Periimplant mucositis is defined by the presence of bleeding and/or suppuration on gentle probing with or without an increased probing depth compared with previous examinations and by the absence of bone loss beyond crestal bone-level changes resulting from initial bone remodeling. Periimplantitis is defined by the presence of bleeding and/or suppuration on gentle probing with an increased probing depth compared with previous examinations and by the presence of bone loss beyond crestal bone-level changes resulting from initial bone remodeling. Thus, a combination of clinical registrations (probing pocket depth, bleeding on probing, and presence of pus) combined with radiographic signs of possible bone loss is needed for differential diagnosis. Conclusions: An accurate baseline registration at the time of placement of the prosthesis (probing pocket depth and bone level) with ongoing yearly monitoring is essential for diagnosis and appropriate disease management.