We used infrared-visible sum-frequency generation spectroscopy to investigate the vibrational properties of the water/poly(ethylene glycol) interface in the 2800-3800 cm(-1) spectral range. The vibrational fingerprint of the interface differs significantly from the one associated with the air/poly(ethylene glycol) interface. It is shown that the poly(ethylene glycol) molecular arrangement, originally relatively well-ordered, becomes disorganised in the presence of water. Moreover, a new OH band is identified demonstrating the strong interaction of water with the polymer.