The modified collagens with rich carboxyls were prepared by chemically modifying collagen, which was firstly extracted by hydrolyzing chrome shavings, using the multi-aldehyde acid compounds (MACs) as the modifiers. Then those modified collagens and the blank collagen were used as scale inhibitors to implement scale inhibition tests. Scanning electron microscope (SEM) and XRD analyses were utilized to characterize morphology and crystal form of calcium carbonate scale. Results showed that the Ca2+ concentration and pH were the main influencing factors within the scale inhibition system, specifically the scale inhibition efficiency would be reduced with the increase of Ca2+ concentration and pH. Both the two types of scale inhibitors were more sensitive to the temperature, i.e., the scale inhibition rates were in a downward trend with augment of the temperature. The crystal form of calcium carbonate could be completely distorted to form a vaterite crystal through the action of modified collagens, thus the scale inhibition effect is achieved. (C) 2012 Elsevier B.V. All rights reserved.