Existing techniques for estimating the weight of udder tissue in live farm animals are based on water displacement (Linzell, 1966) or gross external dimensions (Davis et al,1983). With goats, Linzell (1966) obtained a coefficient of variation (proportion) of 0.02 for a rather laborious casting technique and 0.11 for a water displacement technique. The water displacement technique is difficult to apply with dairy cows owing to the greater size and less accessible position of their udders. The lack of reliable estimates of udder weight limits our ability to assess the efficiency of synthetic tissue. The latter is an important measurement both experimentally and, potentially, inbreeding programmes. The present work investigated the possible use of quick-setting polyurethane foam to prepare udder casts from which udder weight could be estimated. The polyurethane foam used in this study was completely hardened within 30 seconds providing a rapid and easy technique.