A survey by the shopworkers' union Usdaw showed that 4% had been the victim of an attack, the same as last year, although one in six had not made a complaint.
Incidents of verbal abuse fell from 61% to just under half, and the number of threats fell to 34%, from 36% a year earlier.
John Hannett, Usdaw's general secretary said: "I was shocked to learn that 17% of shopworkers who were physically assaulted in the workplace did not report the incident, along with a third of those threatened and almost half of those who were verbally abused.
"This level of under-reporting of incidents is of great concern and my message to shopworkers is very clear - abuse is not a part of the job. We are encouraging our members to report all incidents of violence, threats and abuse."