To evaluate the success of the osseointegration of dental implants in patients with severe maxillary atrophy after sinus lift augmentation and onlay graft surgery with autologous bone grafts.A descriptive and analytic study of 27 patients with severe maxillary atrophy and partial or total edentulism, after 4 years follow-up. All cases underwent to autologous bone graft sinus lift augmentation with or without onlay grafts in the anterior maxillae. After this, reconstruction with osseointegrated implants was performed.After the follow-up period, 89.1% of implants were osseointegrated and loaded. Anterior iliac crest bone graft provides good results with respect to implant osseointegration. The achievement of two surgical procedures for bone grafts surgery and implants surgery, separated 2 or more months, provides better results for osseointegration in comparison to a sole surgical procedure (p<0.01).Implants survival predictability is greater when a second surgical procedure is performed, once bone grafts have experimented an appropriate consolidation. The use of onlay graft and sinus lift augmentation techniques is useful in the resolution of complex problems such as the severe maxillary atrophy.