Measurements are reported for the density of aqueous solutions of 18-crown-6 in the concentration range of 0.1 m to 4.5 m at 25 C. The data is used to obtain apparent and partial molar volumes of 18-crown-6. It is observed that the partial molar volume goes through a minimum at about 2.5 m concentration. The limiting partial molar volume obtained, indicate a large negative limiting excess volume. These results are compared with the similar data reported earlier in D 2 O. It is sugessted that the hydrophobic hydration of the 18-crown-6 is important in dilute concentration range due to which a structure making effect similar to that of apolar solutes is observed.