A series of monodisperse (M-w/M-n < 1.1) poly(ferrocenyldimethylsilane)s was prepared with number-averaged degrees of polymerization, z(n), of 9, 33, 206, and 506 (2-5, respectively), as determined by gel permeation chromatography (GPC). The polymers were studied by small-angle neutron scattering (SANS) in solution with the aim of obtaining the radius of gyration, R-g, the weight-averaged molecular weight, M-w, and the polydispersity index, M-w/M-n. Data were collected over the range 0.008 < Q/angstrom(-1) < 0.5 and for a series of concentrations (weight fraction, w = 0.0063, 0.0125, 0.025, and 0.05). The scattered intensity, I(Q), was fitted to a model based on a Schultz-Zimm distribution of isolated chains with excluded volume. A comparison of the molecular weight and size data determined by GPC and SANS indicated an acceptable agreement between the values for R-g, M-w and M-w/M-n. The results of this study demonstrate the potential utility of SANS to fully characterize metallopolymers, and other polymer systems where traditional methods cannot be applied. (c) 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4011-4020