A report is given on a progeny testing scheme for bacon pigs which operated at Wye College from 1953 to 1957. Boars were brought to the unit, mated to a random selection of sows and 20 progeny (4 pigs from each of 5 litters) were individually fattened under standard conditions. Growth, feed efficiency and carcass measurements were recorded. The data were examined by analysis of variance. Significant differences in most characters were shown between sows, between boars and between tests. There was a progressive improvement in growth performance but not in carcass measurements from the earlier to the later tests. This was attributed in the main to improved management.Differences within litters were small for carcass length but large for backfat measurements. Significant differences between boars could be detected but this was limited by small numbers of boars within tests and the high variability of some characters. The growth performance and carcass characteristics of female pigs were significantly better than for castrated males. Estimates of heritability were fairly high for most characters.Disease incidence declined in the later tests. In earlier tests congestion of lungs associated with virus pneumonia was associated with a slight reduction in speed of growth and feed efficiency.The results are discussed with particular reference to their contribution to the evaluation and utilisation of progeny testing on a national basis.