Measurements of (p, ρ, T) for{xNH 3 + (1 −x)H 2 O} at x= (1.0000, 0.8374, 0.6005, and 0.2973) and at specified temperatures and pressures in the compressed liquid phase were carried out with a metal-bellows variable volumometer between T= 310 K and T= 400 K at pressures up to 17 MPa. The results cover the high-density region from ρ= 345 kg · m −3 for x= 1.0000 to ρ= 878 kg · m −3 for x= 0.2973. The experimental uncertainties at a 95 per cent confidence interval in temperature T, pressure p, density ρ, and mole fraction x were estimated to be less than ±11 mK, ±2.6 kPa, ±2.1 · 10 −3 . ρ, and ±1.8 · 10 −3 · x, respectively. A detailed comparison of the density values with literature data as well as with an equation of state proposed by Tillner-Roth and Friend is also reported.