To investigate the responses of the dominant male, a group of 7 rhesus monkeys was tested on 6 challenge situations including a human with a net and capture of individual animals. Conclusions: (a) At least some dominant male rhesus protect the group, or any member of the group, from external challenges by attacking the source or maintaining a position between the source of disturbance and the group, (b) If the dominant male is restricted in space and the group is challenged, members will approach and remain near him, whereas ordinarily few approach his immediate vicinity.