The demand for bone reconstruction in oral rehabilitation has been growing substantially. However, patients willing to undergo reconstructive surgery want less invasive procedures with less postoperative morbidity. Less invasive bone reconstruction techniques have used bone substitutes to achieve these objectives. However, recent studies about tissue engineering have demonstrated that cell therapy, in combination with bone grafts, may potentially improve the biological characteristics of graft materials. The aim of this study was to histomorphometrically analyse sinus elevation using autologous bone marrow aspirate resulting from the isolation of the bone marrow mononuclear cell fraction, associated with xenogenous graft. Four patients requiring sinus lift procedures before implant placement, with less than 3 mm of residual bone height, where selected for this pilot study. The two patients of Control Group received a xenogenous graft covered by a barrier membrane. The two patients of the Test Group received a xenogenous graft associated with bone marrow mononuclear cell fraction covered by a barrier membrane. Six months after the grafting procedures, bone biopsies were harvested during implant placement and analysed by histomorphometry. Histomorphometric analysis revealed a large amount of vital mineralized tissue (VMT) in Test Group compared to Control Group sites (70+25.46% vs 34+14.14%). For both non vital mineralized tissue (NVMT) and non mineralized tissue (NMT) Test Group showed lower values than Control Group sites (9+12.73% vs 20+26.87% and 21+12.73% vs 46+12.73%, respectively).This pilot study indicated that the clinical use of bone marrow mononuclear cell fraction associated with xenogenous graft in maxillary sinus elevation seems to result in a more adequate bone repair.