Using a homogeneous precipitation method in an ultrasound field, we synthesized nanosized, platelike hydroxyapatite (HAp). The internal structure of these platelike formations consists of specifically oriented and laterally connected nanorods. The synthesized HAp nanorods have a length of about 500 nm and a diameter of about 100 nm. A, closer inspection of the microstructure of a single nanorod revealed a highly regular and defect-free lattice with unique crystallographic plane orientations. The obtained structure was related to the influence of the ultrasound on the growth mechanism. The samples were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and transmission, electron microscopy (TEM).