Six poly(2-cinnamoyloxyethyl methacrylate) (PCEMA) samples with low polydispersity indices were derived from precursors prepared by anionic polymerization. Their intrinsic viscosities were determined in tetrahydrofuran (THF) and chloroform at 25 degrees C and in p-xylene between 55 and 82 degrees C. The data were treated to yield the Mark-Houwink-Sakurada parameters K and a. The a values suggested that THF and chloroform were good solvents for PCEMA at room temperature. The intrinsic viscosity data obtained in p-xylene were also analyzed by the Burchard Stockmayer Fixman method. Both the a values and the results of data treatment by the Burchard Stockmayer Fixman method suggest that p-xylene was a theta solvent for PCEM A at 60 degrees C. Using the K value at the theta temperature, we determined for PCEMA a characteristic ratio of 12.6, which is the ratio between its mean-square end-to-end distance in a theta solvent and that of a random flight chain.