Di-1＇-methylalkyl itaconates and the corresponding poly(di-1＇-methylalkyl itaconates) (PD1＇AI) containing 2-propyl (PDiPI), 2-butyl (PDiBI), 1＇-methylbutyl (PDiAI), 1＇-methylpentyl (PDiHI) and 1＇-methylheptyl (PDiOI) groups as side chains were synthesized and characterized. The polymers were fractionated by fractional precipitation. The fractions were characterized by viscometry in THF and acetone, and by light scattering and size exclusion chromatography in THF. The K-a and a parameters of the Kuhn-Mark-Houwink-Sakurada equations were determined in THF and acetone. The stiffness of the polymer chain was estimated through the rigidity indices, sigma, and the characteristic ratio, C-infinity, using the conformational parameter K-theta obtained from the Stockmayer-Fixman plots. The effect of the side-chain structure on the stiffness, conformational behaviour and glass transition temperatures, T-g, of these polymers is discussed and the results compared with those corresponding to other related polymer analogues.