Abstract: Chenopodium ambrosioides L. (Amaranthaceae), popularly known as "mastruz" or "erva-de-santa-maria", is a perennial plant found in Brazil and used in folk medicine for the treatment of contusions and fractures. The objective of this study was to evaluate the topical effect of a cataplasm prepared from fresh C. ambrosioides leaves on the treatment of fractures experimentally induced in rabbits. Thirty rabbits were divided into three groups (n = 10). After anesthesia, a radius fracture was created and the animals received topical applications of C. ambrosioides cataplasm (MZG), diclofenac sodium (DG) and isotonic solution 0.9% NaCl (Control). At 30 days, we evaluated the animal bone regeneration through both qualitative macroscopic analysis of the fracture focus as by determination of serum alkaline phosphatase (ALP). The evolution of bone repair has been verified at 30 and 45 days through the histological analysis. No significant difference in ALP levels was observed between groups. In addition, no allergic reactions or impairment of tissue adjacent to the fracture focus were seen in any of the groups. In contrast, although all groups exhibited similar tissue architecture, the histological analysis revealed greater formation of mature bone tissue in MZG at 30 days, when compared to DG and control group. In addition, higher collagen fiber density was observed in MZG at 45 days. These results indicate Chenopodium ambrosioides as a promising therapeutic agent for bone regeneration. The plant may be useful as a raw material for the production of biomaterials for fracture healing, contributing to its validation in ethnomedicine.