Direct composition measurements are made on equilibrium vapour and liquid phases of a five-component model gas condensate sample. The compositions of equilibrium phases are measured at two temperatures (303.15 and 353.15 K) and pressures of 30.44-19.41 MPa. Component balance calculations and evaluation of the internal consistency of the measured equilibrium ratios of components demonstrate the reliability of measurements. (C) 2003 Elsevier Science B.V. All rights reserved.