The movements of replacement breeding cattle have been implicated in the spread of many economically important cattle diseases. In this analysis, records from the Cattle Tracing System database were used to investigate the frequency and characteristics of replacement breeding cattle trade in Great Britain. During the 2006 calendar year, an estimated 48.7 per cent of beef herds and 47.8 per cent of dairy herds purchased at least one replacement breeding animal. Open beef herds purchased an average of 7.2 replacement animals (median: 4, range: 1-819) from 3.6 source herds (median: 2, range: 1-114), while open dairy herds purchased an average of 13.7 replacement animals (median: 7, range: 1-827) from 5.2 source herds (median: 3, range: 1-146). The most common animal types purchased by beef and dairy herds were open heifers and open lactating cows, respectively. Although the movements of purchased replacement breeding cattle accounted for only 13 per cent of individual movements in the between-herd contact network, they had a disproportionately strong influence on the risk of disease spreading through the industry as evidenced by their high betweenness centrality scores. These results emphasise the importance of ensuring that good biosecurity programmes are in place to prevent disease transmission. [ABSTRACT FROM AUTHOR]