When reducing fat content or replacing fat with thickener in reduced fat foods, flavour and texture may change. The objective of this study was to investigate effects of thickener and fat content on flavour and texture in low-fat foods. We used sourmilk with 0.1% or 4.2% fat where odour compounds with differing polarity, maltol or ethyl 2-methylbutyrate, were added. Sourmilk with: O.1 g 100 ml(-1) or 0.5 g 100 ml(-1) gelatine; 0.05 g 100 ml(-1) or 1.O g 100 ml(-1) pectin; or 0.65 g 100 ml(-1) or 0.9 g 100 ml(-1) xanthan added, and sourmilk without any thickener added, for each of the two odour compounds were manufactured. Sensory evaluation by descriptive profiling and viscosity measurements by Bohlin VOR were made. Perceived thickness increased with higher fat content and with increased concentration of thickener. Viscosity (measured by a Bohlin rheometer) did also increase with higher fat content and with increased concentration of thickener. Smell and flavour of maltol increased with higher fat content, while smell and flavour of ethyl 2-methylbutyrate were unaffected. Smell and flavour of the maltol were unaffected by all the thickeners, while smell and flavour of the ester were affected. Sourness was masked by all the thickeners.