The egg white sol becomes opaque gel by heat treatment, and the gel turns transparent on dehydration. In the present study, the structural change during the dehydration process was examined by small angle neutron scattering experiment; the data was fitted based on the Guinier and Ornstein-Zernike (O-Z) theories. The Guinier plot clarified the structure with the dimension of about 2.8 nm, which was almost independent of the water content. The correlation length derived from the O-Z plot became larger from 9.5 to 17.3 nm as the water content decreases. (C) 1998 Elsevier Science B.V. All rights reserved.