Objectives Liver biopsy is a valuable clinical tool, but for the interpretation to be meaningful a certain core size should be obtained. This study examines the changes the liver biopsy core undergoes during processing steps. Methods A total of 61 consecutive percutaneous liver biopsies were obtained between November 2004 and April 2005. The needle type utilized was the 16-gauge automatic tru-cut. A measurement was made while each liver biopsy core specimen resided in the cartridge, then a measurement was made with the core placed on the tray, and a final measurement was made after the pathologist received the formalin-fixed specimen. Results The mean size of the biopsy core in the cartridge measured 15 ± 2 mm, compared to a mean size on the tray of 19.6 ± 3.5 mm, and a mean size after fixation of 18.3 mm. All mean sizes were statistically different from one another. The compressive effect of the cartridge was 23%. The shrinkage effect of formalin fixation was 7%. Conclusions The liver biopsy core size changes significantly through the processing steps. It is imperative that the operator is aware of these changes so that appropriate decisions are made. As an example, if the operator underestimates the core size when measured in the cartridge, a second pass may be completed when in fact adequate tissue had been obtained on the first pass.