Herein, well-defined nanoscale Ag2S and Ag2Se dendrites, which represent a novel morphology of silver chalcogenides, were successfully synthesized using a template-based method at room temperature and ambient pressure. It was found that the template and ultrasonic wave played important roles in the formation of well-defined dendrites. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and elemental analysis. The optical properties of the products were also recorded by means of UV-Vis absorption spectroscopy, indicating that the products were within a quantum confinement regime. Finally, the formation mechanism of dendrites was also investigated.