The aim of this study was to examine the effect of ultrasound treatment on physical properties of soy proteins. For this purpose, soy protein isolates (SPI) and soy protein concentrate (SPC) were treated with ultrasound 20 kHz probe and ultrasound baths (40 and 500 kHz) system. In this study ultrasound treatment affected significant changes in texture of model systems prepared with soy protein concentrates, that gelled during ultrasound treatment with probe 20 and 40 kHz bath for 15 min. Model system prepared with SPI creamed during ultrasound treatment with probe 20 kHz for 15 min. Treatment with 20 kHz probe ultrasound lead to significant changes in conductivity, increased solubility for SPC, significantly increased specific surface area that is of interest in food texture and increased values of emulsion activity index. Weight mean diameter and volume-surface average diameter decreased significantly for all samples and all treatments. Flowing behaviour of SPI and SPC model systems has been greater influenced by ultrasound treatment. There was no improvement in foaming and emulsifying properties of soy protein model systems after 500 kHz bath treatment. (C) 2009 Elsevier Ltd. All rights reserved.