Six high molar mass polyglycidol samples were obtained by fractionation of polyglycidol synthesized by means of cationic polymerization of ethoxyethyl glycidyl ether followed by cleavage of the protective groups. The fractions covering the molar mass range from 0.1 to 2.4 x 106 were studied by dynamic and static light scattering. The weight-average molar masses (MW), second virial coefficients (A(2)), radii of gyration (R-h), diffusion coefficients (D-0), hydrodynamic radii (R-h), and dynamic virial coefficients (kD(phi)) were determined for the single coil in dilute aqueous solution at 25 degrees C, and scaling equations were established. It was found that polyglycidol in water does not exhibit the expected asymptotic good solvent behavior. The scaling exponents for A(2), D-0, and Rh are even closer to those for polymer coils in marginal solvents than to the expected ones in the excluded-volume region. The values of the interpenetration parameter, psi, and kD(phi) are far from reaching limiting values even for the fractions of the highest molar masses. The scaling exponent for R-g as well as the R-g/R-h ratio, which was found to increase with increasing molar mass, imply elongated coil conformation in the high molar mass region.