Abstract: Changes in social hierarchy were evaluated in a herd of 3-year-old Hanoverian geldings. One group (n = 5) was exposed to a training programme, the other (n = 5) remained untrained. After 6 months, the groups were reversed. Hierarchical positions were evaluated by field observations and/or paired-feeding tests at the beginning, the middle, the end of the first and at the end of the second training period. Both methods yielded identical results. Almost all horses changed position in only one direction: either up or down. Neither increase in aggression nor mutual injuries were recorded during the whole experiment. No statistically verified differences in dominance ranking occurred between trained and untrained groups, but apparent differences were consistent. Thus, if horses are kept in the same group for a longer period of time, exercise induced changes in hierarchy are probably of minor importance and are unlikely to increase the incidence of injuries. This may have implications for the promotion of group-housing for sport horses.