The sedimentation and diffusion of poly(ethylene glycol) (PEG) with weight average molecular weight (M-w) from 5 x 10(2) to 2 x 10(5) g/mol have been investigated by use of an analytical ultracentrifuge (AUC). The sedimentation velocity analysis based on the Lamm equation gives the sedimentation coefficient (s) and diffusion coefficient (D). Our study reveals that the sedimentation coefficient (s(0)) and diffusion coefficient (D-0) at infinite dilution scale to molecular weight (M-w), namely, s(0) = KsMw alpha, with K-s = 6.14 x 10(-3) and alpha = 0.469 +/- 0.008, and D-0 = KDMw-beta, with K-D = 1.43 x 10(-8) and beta = 0.576 +/- 0.007.