Measurements were taken on 36 laying hens, 46 growing female turkeys and 36 broiler chickens using modified abdominal fat calipers to determine the prediction of abdominal fat in different classes of poultry. Four pairs of caliper measurements were taken on each bird by three operators (layers and turkeys) and one operator (broilers). The live laying hens and the plucked turkey carcasses were also scored for fatness. The caliper measurements were significantly related to the proportion of abdominal fat (g abdominal fat/kg body weight) in all three groups of birds. The correlation was greater in laying hens (0.81) and turkeys (0.76) than in broilers (0.51). There were significant operator effects upon the prediction of abdominal fat. In each case the measures obtained by two practised operators gave better prediction of abdominal fat than those from an unpractised operator.The calipers were simple to operate, inexpensive and robust. Measurements were quickly taken (approximately 4 pairs/min) and the results were easily interpreted. These factors suggest that the calipers may have use not only in poultry breeding and research work but also in on-farm monitoring of a commercial flock in order that their body fat content could, if necessary, be modified (for example by diet or environment) prior to slaughter.