Measurements of (p, rho, T) for NH3 at specified temperatures and pressures in the compressed liquid phase were carried out with a metal-bellows variable volumometer along 10 isotherms between T = 310 K and T = 400 K at pressures from the vapour pressure to p = 17 MPa. The results cover the high-density region from rho = 343 kg . m(-3) to rho = 601 kg . m(-3). The experimental uncertainities in temperature T, pressure p, and density rho were estimated to be less than +/-4 mK, +/-1.0 . 10(-3) . p, and +/-1.0 10(-3). rho, respectively. Measurements of the vapour pressure and saturated liquid density at temperatures from T = 310 K to T = 400 K are also reported. On the basis of the present results, the isothermal compressibility and the cubic expansion coefficient are illustrated as a function of temperature and pressure.