A study was undertaken to assess the effect of different animal types (pigs representing different cross-breeds and/or different fattening systems) on a control method, also called referee method, partial dissection method or substitute reference method, being a tool in the calibration procedure for pig carcass classification. The calibration procedure serves here for finding an accurate prediction equation between the reference method and the rapid, on-line instrumental method for assessing the lean content of pig carcasses. Such, rather simple control methods have to show a close relationship with the time- and labour consuming reference method, the latter serving for direct determination of true lean content. Its application makes a partial substitution of the reference method possible, considerably reducing experimental labour, time and cost of calibration. In these experiments, contrary to expectation, a marked animal type bias could be observed with the applied control method (using the weight of the four main joints of the carcasses without hide and sub-cutaneous fat), however, the differences in the estimated lean contents were not excessive and it appears that the practical application is not hindered. As shown in this paper, the systematic differences are due to the animal type specificity of the relationship between the lean-meat and intermuscular fat content of the joints. The bone content of the joints does not seem to have any influence in this respect. (c) 2004 Elsevier Ltd. All rights reserved.