This published data collection contains three large volume datasets obtained by X-ray tomographic microscopy of the full juvenile rat lung structure at micrometer resolution. Data were collected and processed at the TOMCAT beamline X02DA of the Swiss Light Source. The first dataset contains the full scanned volume reconstruction (ca. 1.2 Tb), while a second one contains the same data but cropped down in size to the smallest bounding box encompassing the entire lung structure. The third dataset is a binarized version of the second one after thresholding operations to segment out the air volume of the lung.