Purpose: Ultrasound therapy induces clinical healing of irradiated avascular mandibular bone and fractures. In vitro ultrasound in tissue culture has been shown to stimulate bone formation synthesis and bone remodeling factors and to stimulate osteoblast proliferation. Therefore, the aim of the present study was to investigate the effect of short-wave (1-MHz) and long-wave (45-kHz) ultrasound on the vascularity of the chorioallantoic membrane (CAM) of a fertilized egg. Materials and Methods: The nature of the angiogenic effect was investigated using the CAM of a fertilized egg by: (1) application of sonicated fibroblast media incorporated into methylcellulose disks onto the CAM and (2) direct application of the ultrasound, using both long-wave (45-kHz) and short-wave (1-MHz) frequencies at a range of intensities, to the surface of the egg. Angiogenesis was assessed quantitatively by three independent observers. Results: Both ultrasound methods showed evidence of an angiogenic effect compared to controls. The most effective results were seen with direct application of a 45-kHz wave at an intensity of 15 mW/cm2 and indirect application of the media of fibroblasts ultrasonicated at 1 MHz with an intensity of 0.4 W/cm2. Conclusion: This model confirms that ultrasound can induce neoangiogenesis in vivo. Schlagwörter: angiogenesis, bone, chorioallantoic membrane culture, osteogenesis, ultrasound