The aim of the study was to test whether or not, for primary bone augmentation, the use of a xenogenic bone block loaded with rhBMP-2 results in similar bone quantity and quality compared to an autogenous bone block and to evaluate patient morbidity following the surgical procedure with the two treatment modalities. 24 patients requiring implant therapy for the reconstruction of 1 to 4 missing teeth and insufficient bone volume for implant placement were randomly assigned to receive one out of two treatment modalities. Both treatment modalities were successful in regenerating bone to allow for dental implant placement at 4 months. Histologically, a higher amount of mineralised tissue was observed for the control group at 4 months. The use of a second surgical site in the control group tended to a higher patient morbidity compared to the test group, but did not reach statistical significance. Schlagwörter: dental implants, guided bone regeneration, growth factors, bone morphogenetic protein-2, autogenous bone blocks