A Vietnam War veteran has appealed for help in finding his missing war medal after he lost it during Anzac Day commemorations.

Ron Emerson, who served as a lance corporal and a section commander in Vietnam between 1968 and 1969, lost his Vietnam service medal at the dawn service at the Australian War Memorial in Canberra.

Ron Emerson lost his Vietnam service medal during the Anzac Day dawn service at the war memorial. Credit:Karleen Minney

Mr Emerson, who now lives in Canada, said he put on the medal before leaving the Hyatt Hotel on Thursday morning but, by the time the dawn service had ended, the medal had disappeared.

"I only ever wear it on Anzac Day, I don't wear it any other time other than that," Mr Emerson said.