Advanced atrophy of the partially edentulous maxilla necessitates bone augmentation as a prerequisite for successful implant osseointegration. This case shows that sinus grafting at the left first molar (free-end gap) by means of particulated mineralized solvent-preserved cancellous bone and sealing of the recipient site with a bioabsorbable xenogenic collagenous membrane provides optimum conditions for a staged implant placement. Four months after sinus membrane elevation, a trephine biopsy was recovered from the augmented floor and a microtextured implant placed into the augmented area. The ultrastructural observations testify to the biocompatibility and osteoconductivity of the grafting material used. Schlagwörter: bioabsorbable membrane, delayed placement, grafting, microtextured implant, mineralized allograft, sinus floor elevation, transmission electron microscopy