Objectives: The aim of this prospective clinical trial was to evaluate the success implant rates during 24 months using OSFE procedure without grafting materials. Study Design: 42 adult patients (22 female, 15 male) were selected according to Nedir et al ?s inclusion criteria of which 5 patients were excluded, due to periapical pathology in adjacent teeth (n=3) and treatment with bisphos - phonates (n=2). 37 patients aged 31-68 years were selected. Smokers were divided in two groups depending on the number of cigarettes consumed per day (a) 0-10, (b) 11-20. One patient was excluded because he was lost to follow- up at 24 months A total of 36 threaded implants were placed, | 4,1mm Straumann® (Straumann AG, Waldenburg, Switzerland) and | 3,5mm Klockner® (Klockner Implant System, Barcelona, Spain). The most used implant dia - meter was 4,1 mm (n=29), followed by 3,5 mm (n=7), and length used was 10 mm (n=32) and 8 mm (n=4). Initial RBH ranged from 4 mm to 9 mm. All statistical data were processed using the program R 3.0.2 for windows. Results: A total of 36 threaded implants were placed. Residual bone height (RBH) at implant placement averaged 7,4 ± 0,4 mm. Mean bone gain was 1,8 ± 0,3 mm. Four implants showed a bone gain exceeding 3 mm. Mean im - plant protrusion length into the sinus amounted to 2.1 ± 0,3 mm. Regarding the relationship between smoking and periodontal probes, no statistically significant differences were found ( P =0,25), neither in relation to the number of threads that the implants showed ( P =0,29) or bone gain ( P =0,79). After 24 months the implant success rate was 91,6%. Conclusions: Implant rehabilitation of edentulous atrophied posterior maxilla can be safely performed and simpli - fied using the OSFE technique without grafting with reliable long-term results.