Carboxymethylcellulose (CMC) was used as a stabiliser for acidified whole milk drinks. The stability of the acidified whole milk drinks was investigated by observation of the evolution of size and zeta potential of colloidal particles during acidification along with sedimentation measurement and was compared with the stability of acidified skim milk drinks. It was found that the presence of fat resulted in larger particle sizes, but it did not disturb the absorption of CMC onto casein micelles below pH 5.2. The absorption of CMC endows the casein micelles with electrostatic and steric repulsions, essential to the stability of the acidified milk drinks. Acidified whole milk drinks can be stabilised by CMC, which is capable of effectively preventing the unwanted creaming of fat embedded in the clusters of CMC and caseins as well as preventing the aggregation of casein micelles as it did in skim milk drinks.