Size variation of Sus remains within and between sites is examined for the Neolithic sites in the Wei River valley in China. The coefficient of variation [V] for pig measurements at the sites of Wayaogou, Quanhucun and Jiangzhai was calculated, and we observed patterns that show evidence of two populations of different-size pigs, supporting the likelihood that both wild and domestic pigs were present. Also, size reduction of pigs can be traced within the Neolithic-early Bronze Age archaeo-faunal sequence of the Wei River valley. This size reduction was accompanied by an increase of coefficients of variation through the Neolithic. Both of these trends were probably the consequences of pig domestication, and the morphometric differences probably provide evidence for the different stages of pig domestication in this region. Copyright © 2013 John Wiley & Sons, Ltd.