This paper presents a trial and error method for determining the optimal values of k andaof the Mark-Houwink equation using polymers with different intrinsic viscosities ([η]) and molecular weight distribution (MWD) as standards. The values of k andafor polystyrene, EP-copolymer, polypropylene, polyethylene, polyvinylchloride, and polycarbonate, etc., have been determined with this method. The relative errors of the resultant [η] are below 6%, 4% or 3%. The viscosity-average molecular weight (Mv) of polystyrene standards agrees well with those of Pressure Chemical Co.; the weight- and number-average molecular weights of EP-copolymer coincide with that measured by using the low angle laser light scattering KMX-6 and the Knauer membrane osmometer, respectively. Thus, the method possesses high precision and can be applied to polymers with a wide range of molecular weight (MW) and molecular weight distribution (MWD).