In this work, the X-ray microtomography (mu CT) technique was used for the analysis of fat microstructure and quantification of fat in four types of mayonnaise. The dynamic-mechanical properties of the mayonnaise samples were also studied using a controlled-strain rotational rheometer. Four types of commercially produced mayonnaises, chosen to exhibit variability in terms of visible structure of fat, were used for this experiment: 'kraft', 'calve', 'kraft legeresse' and 'calve-mayo'. Appropriate quantitative three-dimensional parameters describing the fat structure were calculated. With regards to the microstructural and rheological relationship, results from the correlation carried out show that a correlation exists among some microstructural and rheological parameters of the mayonnaise samples. The results from this study also show that mu CT is a suitable technique for the microstructural analysis of fat as it does not only provide an accurate percentage volume of the fat present but can also determine its spatial distribution. (C) 2011 Elsevier Ltd. All rights reserved.