A new methodology for the estimation of drop size distributions in dilute polydisperse polymer blends is proposed. The procedure exploits the capabilities of large amplitude oscillatory shear (LAOS) flows to discriminate the behavior of drops of different size. The methodology is tested on synthetic data obtained by mimicking theological responses of polydisperse immiscible polymer blends. The procedure allows a quantitative description of the original distribution, and is also robust to experimental noise. (c) 2007 Elsevier B.V. All rights reserved.