The aim of the present investigation was to evaluate the clinical and histologic results of a sinus augmentation procedure performed using calcium sulfate as the grafting material. A group of 12 patients (15 sinuses) formed the pilot group. Based on the experience of the pilot group, the technique of calcium sulfate application was modified, and a second group of 45 patients (50 sinuses) was subsequently treated (test group). In the pilot group, a total of 30 implants (Biolock) was placed. In the test group, a total of 100 implants (Biolock and Biohorizons) was placed. The clinical data reported in the present study are related to the 1-year follow-up for both groups. Clinical evaluations, including assessment of implant mobility and probing pocket depth, were recorded on a monthly basis following implant uncovering until final prosthesis placement, and every 6 months thereafter. Radiographs were taken prior to sinus augmentation, monthly until 6 months postoperatively, 9 and 12 months after implantation, and at yearly intervals thereafter. One implant in the pilot group was not integrated at second-stage surgery, and 1 in the test group failed to maintain osseointegration after the abutment connection (at the 1-year evaluation). Based on defined criteria, the overall success rate for the 130 placed implants 1 year postimplantation was 98.5%. Clinical and radiographic evaluation revealed that the augmentation procedure resulted in new tissue formation within the sinuses. The technique used in the test group suggested a slowdown in material resorption and a reduction in graft shrinkage during healing. Bone biopsies were harvested for histologic evaluation. The application of a resorbable barrier membrane to the access window reduced the invagination of soft tissue at that level. The results of this study support the hypothesis that calcium sulfate may be a suitable material for sinus augmentation. Schlagwörter: calcium sulfate, dental implant, histology, implantology, maxillary sinus augmentation, oral surgery