The intrinsic viscosity [η] of poly(3,5-dimethyl-phenyl-acrylate) (35PDMPA) solutions were evaluated throughout the measurements of the flow times of toluene and polymer solutions by classical Huggins, and Kraemer's methods using a Cannon-Ubbelohde semi-micro-dilution capillary viscometer in a Cannon thermostated water bath at 40˚C ± 0.02˚C. The values of Huggins' constant estimated ranged from 0.2 to 0.4 which were within expectations. The intrinsic viscosities and molecular weight relationship was established with the two-parameter classical models of Staudinger-Mark-HouwinkSakurada and Stockmayer-Fixman. Conformational parameter C ∞ and σ indicated 35PDMPA be semi flexible. Also, the rigidity of 35PDMPA was confirmed by Yamakawa-Fuji wormlike theory modified by Bohdanecký. The molecular parameters were estimated and compared. The results showed that 35PDMPA behaves like a semi-rigid polymer in toluene at 40˚C rather than a random coil flexible macromolecule.