Microfocus computer tomography (mu CT) is a non-destructive technique for imaging internal features within an opaque object. Among the most important recent improvements of mu CT is its resolution of about 10 mum in three dimensions, which is much better than that obtainable with medical CT. The advantage of mu CT versus classical light microscopy is that three-dimensional petrographical information becomes available. The results from two complementary microfocus instruments are presented. The two instruments can accept different object sizes, ranging from a few millimetres to several centimetres in diameter. As a consequence, downscaling of petrographical features is possible both from medical CT to mu CT and within mu CT research. Apart from the possibilities of visualisation. attention is paid to the quantitative measurements that can be obtained from mu CT research which enables petrographical data to be linked to petrophysical data. (C) 2001 Elsevier Science Ltd. All rights reserved.