Vapor-liquid equilibrium and liquid density were measured for the three binary systems water + tetraethylene glycol (TEG), ethanol + TEG, and 2-propanol + TEG at 298.15 K. The experimental apparatus employed for the vapor-liquid equilibrium measurement was based on a flow method, and that for the liquid density was a vibrating tube method. The activity of water showed the negative deviation from Raoult＇s law, while that of ethanol was almost proportional to the mole fraction of ethanol. For the 2-propanol + TEG system, the positive deviation could be seen. The liquid density for water + TEG showed the negative excess volume for the whole range of the mole fraction. The experimental data were correlated with the Peng-Robinson (PR) equation of state using the mixing rule proposed by Wong et al. and Orbey et al. The calculated vapor pressures showed good reproducibility for the three binary systems. The calculated density was not shown for the water + TEG system.