A novel series of bio-based hyperbranched polymers, i.e., hyperbranched polyterpene alcohols, were prepared by the cationic ring-opening polymerizations of citronellol oxide (1) and nopol epoxide (2) using boron trifluoride diethyl etherate (BF3 center dot OEt2) as the catalyst. The polymerizations of 1 and 2 homogeneously proceeded without gelation to produce organic solvent-soluble polymers (poly-1 and poly-2, respectively). The absolute weight-average molecular weights (M-W,M-MALLS), which were measured by a multiangle laser light scattering instrument (MALLS), were 3700-6200 g mol(-1) for poly(-1) and 9000-20 000 g mol(-1) for poly-2, which were ca. 1.4-4.8 times greater than the relative molecular weights (M-W,M-SEC) measured by size exclusion chromatography (SEC). The intrinsic viscosities ([eta]) of these polymers were very low in the range of 8.5-10.1 mL g(-1) for poly-1 and 5.9-9.5 mL g(-1) for poly-2. The Mark-Houwink-Sakurada exponent alpha was calculated to be 0.32-0.40 for poly-1 and 0.25-0.35 for poly-2. These results of the MALLS, SEC, and viscosity measurements suggested that these polymers exist in a compact spherical conformation in solution.