Bone regeneration with demineralized bone preparations has demonstrated its potential in grafting procedures in surgical disciplines of both medicine and dentistry. To improve the effectiveness in preparation and osteogenic regeneration, we developed a simple and rapid demineralizing method for osteogenic allograft preparation and evaluated its osteogenic effect using an ectopic bone formation assay. The rat diaphyseal cortical bones were demineralized in heated 0.6N HCl at 60° C for 10 to 30 mins using a controlled-heat ultrasonic cleaner, washed with sterilized distill water, and dehydrated with graded alcohol after 30% H2O2 treatment. The prepared grafts were implanted in rat dorsal subcutaneous pouches for 1-3 weeks and then the harvested tissue samples were prepared for routine light microscopic observation. The allografts demineralized with 60°C HCl for more than 20 mins in an ultrasonic condition were completely demineralized and effectively induced ectopic formation without specific pathologic findings. These findings suggest that demineralization with 60°C HCl for around 20 mins using a controlled-heat ultrasonic cleaner and dehydration with graded alcohol after short treatment with 30% H2O2 is a very simple but effective osteogenic allograft preparation method with minimal antigenicity and sterilizing effects.