We are appealing for witnesses following an incident which occurred on a bus between Amesbury and Larkhill.
The incident happened on 11 November at approximately 1.42pm.
It is understood that a man shouted racist abuse at the female bus driver.
PC Jonathan Brunt said: "This behaviour is unacceptable and left the victim feeling upset and frightened.
"We believe several members of the public witnessed the incident and we would like to speak to them. If this was you, please call police on 101. The information you have could really help our investigation."
A 40-year-old man has been interviewed under caution in relation to this incident.
Alternatively, call Crimestoppers anonymously on 0800 555 111.