The (p, rho, T) behaviour of liquid 3,3,3-trifluoropropene (R-1243zf) was investigated in the temperature range from T = (203.23 to 293.72) K at pressures from p = (1.04 to 15.22) MPa utilizing a vibrating-tube densimeter. This work extends measurements of the refrigerant R-1243zf by 109 data points into the low-temperature and high-density region. A physically based and a polynomial model were used to calculate density from the measured values (temperature, pressure and oscillation period). The physically based model was used to present the densities while the polynomial model contributes to the estimate of their uncertainty. The combined expanded uncertainty (k = 2) of the experimental densities was estimated to be 1.7 kg center dot m(-3). The reference equation of state of R-1243zf as implemented in NIST's REFPROP 10.0 database deviates from the experimental data up to 2.0 %. To improve upon this representation, a genetic programming based symbolic regression approach was used to correlate data reported in the literature and measured in this work for liquid R-1243zf in the density range between (700 and 1240) kg center dot m(-3). The new density correlation agrees with the experimental data within 0.2 %.