The purpose of this study was to examine the effect of addition of different hydrocolloids’ mixtures on rheological properties and syneresis extent of set yoghurts. The hardness and syneresis values of set yoghurts without polysaccharide addition were >33 G and 2% respectively. The yoghurts with guar gum (GG) and xanthan gum (GK) addition exhibited the slight increase in hardness values with the increase of the polisaccharide concentration added. In the case of xanthan gum (GK), the increase of polysaccharide concentration decreased the level of syneresis. The addition of xanthan gum-guar gum (GK-GG) mixture, higher than 0,01% caused the decrease of syneresis to the values which were lower than those recorded for the control yoghurt sample. Among the individual polysaccharides, the yoghurts with the best rheological properties and the lowest syneresis were obtained with the addition of xanthan gum.