The dilute solution properties and conformational characteristics of poly(n-octadecyl acrylate) have been studied. The comb-like polymer obtained by radical polymerization of octadecyl acrylate was fractionated by both methods of fractional precipitation and fractional solution. The average molar mass and the polydispersity index for the polymer fractions studied were found to be in the range of 0.62-80.9×10² kg/mol and 1.12-1.76, respectively. The solubility parameter found for the polymer was 8.65 (cal.cm^-3)^1/2. A phase equilibrium experiment yielded the T_θ as 11.5℃ in CH₂Cl₂. The unperturbed chain dimension of the polymer was calculated by using intrinsic viscosity data. The conformational characteristics under unperturbed state were analyzed by an application of theories for both the flexible chain and semi-flexible worm-like model . The results indicate that the flexibility of the backbone chain of the polymer is reduced to an extent that can be comparable with a typical semi-stiff chain.