Hydroxyapatite nanostructures with various shapes have been prepared by phosphate surfactant self-assembly in aqueous solution. The hydroxyapatite structure is greatly influenced by the sodium dodecyl phosphate (SDP) concentration. X-ray diffraction, transmission electron microscopy measurements, thermogravimetric analysis, and Fourier transform infrared spectra were performed to investigate the nanostructures. Spindle-type nanoparticles formed by oriented attachment of hydroxyapatite nanocrystals were obtained with low SDP concentration, whereas rod-shaped and sheet-like nanostructures formed in the two-dimensional water phase of the lamellar structure with high SDP concentration. These results indicate that SDP molecules play a critical role in formation of hydroxyapatite nanostructures. (C) 2018 Elsevier B.V. All rights reserved.