Molecular weight distributions in poly(vinyl chloride) resins have been determined from simple viscosity measurements. Ratio of 11% solution viscosity to intrinsic viscosity yielded a figure which has been correlated with molecular weight distributions obtained (1) from the ratio of weight-average to number-average molecular weights and (2) from gel permeation chromatography. Ratio of viscosities is thus a useful short-cut technique for obtaining approximate molecular weight distributions in poly(vinyl chloride) resins which have 0. 77 < [η] < 1.15 and 1. 6 < ROM < 2. 8.