Laboratory- and rotating- frame spin-lattice relaxation times (T₁ and T_1ρ) of ¹H and ¹³C in lyophilized poly(vinylpyrrolidone) (PVP) and methylcellulose (MC) are determined to examine feasibility of using T₁ and T_1ρ as a measure of molecular motions on large time scales related to the storage stability of lyophilized formulations. The T_1ρ of proton and carbon was found to reflect the mobility of PVP and MC backbones, indicating that it is useful as a measure of large-time-scale molecular motions. In contrast to the T_1ρ, the T₁ of proton measured in the same temperature range reflected the mobility of PVP and MC side chains. The T₁ of proton may be useful as a measure of local molecular motions on a smaller-time-scale, although the measurement is interfered by moisture under some conditions. The temperature dependence of T₁ and T_1ρ indicated that methylene in the MC molecule had much higher mobility than that in the dextran molecule, also indicated that methylene in the PVP side chain had a higher mobility than that in the MC side chain.