The study of the viscometric results obtained with a great number of worm-like polymer-solvent systems showed that plotting the variation of the logarithm of the intrinsic viscosity versus the logarithm of the molecular mass of these polymers we observe two crossover points. The first crossover point corresponds to a molecular mass equal to the molecular mass of one Kuhn statistical segment. The second crossover point appears when we reach the complete excluded volume behavior and depends on the quality of the solvent. These two crossover points delimit three molecular mass regions. We indicate the methods to obtain the statistical segment length of worm-like polymers in each of those molecular mass regions. A new method is proposed in order to obtain the statistical segment length of the worm-like polymers based on the Han＇s equation (Han CC. Polymer 1979; 20:1083) derived from the blob theory. (C) 2000 Elsevier Science Ltd. All rights reserved.