Introduction: The need to obtain bone substitutes capable of assisting in the regeneration of large defects drives the research towards the development of new synthetic biomaterials. Objective: To evaluate the biological behavior of two experimental bioceramics (AA and U) in the regeneration of critical bone defects. Material and Method: Biomaterials composed primarily of monetite supplemented with zinc, silica gel and hidroxyapatite, with particles between 0.25 to 1.0 mm in size, were implanted in similar amount in defects with 8.5 mm diameter made in calvarias of Rattus norvegicus. The animals were sacrificed at 15 days, after surgery. The calvarias were collected, processed, analyzed histomorphologically in comparison to a negative control with blood clot (C-). Procedures approved by CEUA/UEFS/BR, Protocol 12/11. Results: In all groups there was little acute inflammation. Group C- showed only reactive bone formation at the edges and fibrous tissue in the defect area. However, in implanted groups, especially in AA, most of the particles were slightly degraded and surrounded by osteoid matrix, probably due to the wide availability of bioactive ions such as calcium, phosphate and zinc released due to monetite solubilisation. Conclusion: It was concluded that both biomaterials are biocompatible but AA was more osteogenic than U. More studies in others biological points are necessary. Clinical Implications: The development of a resorbable biomaterial which accelerates bone regeneration is relevant for orthopedics and dentistry, and can lead to a decrease of morbidities. Financial Sources: Study supported by CAPES, CNPq and FAPESB. Keywords: Biomaterial, Osteogenesis, Monetite, Hidroxyapatite, Silicon, Zinc