Purpose: To explore risk indicators potentially associated with early apical peri-implantitis (EAP). Materials and methods: A retrospective survey was performed in 2017 with recorded information from patients receiving dental implants between 1996 and 2016. Reporting follows the STROBE (strengthening the reporting of observational studies in epidemiology) guidelines. Data were collected from the medical histories and radiographs: diagnosis of EAP (health/disease), gender, age, type of surgery (immediate/delayed placement), implants placed (position, width, length, location, mesial and distal tooth-implant distance measured at the apex, state of the adjacent tooth and tooth being replaced, and surgical complications. Once the EAP had developed, data were collected regarding days of evolution, symptoms, signs and radiological findings. Results: A total of 2548 patients (57.1% females and 42.9% males) with 8110 implants were enrolled in the study. 46 patients with 58 implants were diagnosed with EAP – 23 in the maxilla (39.6%) and 35 in the mandible (60.4%) – between 6 and 50 days after implant placement, with a mean period of 21.7 days (SD 10.1). The frequency of EAP was 1.81% in patients and 0.71% in implants. Immediate placement multiplied the odds of developing EAP 21-fold (95% CI 6.74 to 65.7; P 0.001) versus delayed placement. The existence of an apical lesion in the tooth being replaced multiplied the odds of developing EAP 26.3-fold (95% CI 4.24 to 162.8; P 0.001). Replacing a tooth endodontically treated increased the odds 3.48 times (95% CI 0.99 to 12.3; P = 0.052). The presence of an adjacent endodontically treated tooth increased the odds 0.97-fold (95% CI 0.26 to 3.60; P = 0.963). An apical mesial distance of ≤ 1.5 mm increased the odds up to 5.12-fold (95% CI 2.12 to 12.4; P 0.001). Conclusions: The presence of endodontic periapical lesions or endodontic treatment in the tooth being replaced, immediate implant placement or mesial tooth-implant distance measured at the apex were significantly associated with increased odds of EAP. Schlagwörter: early apical peri-implantitis, implant failure, implant periapical lesion, retrograde peri-implantitis Conflict-of-interest statement: The authors declare no conflicts of interest in relation to this study.