The objective of this study was to investigate the possibility of using X-ray computer tomography (CT) for measuring average moisture content (MC) and shrinkage of biological products that are dried as granular materials. Three different biological materials were dried simultaneously under the same drying conditions, namely, spruce sawdust and two species of mushrooms. The results showed that moisture content values within approximately ±1% of the oven-dry values and linear relationships between shrinkage and MC can be obtained without any calibration factor and a limited number of CT-images.