100 Đồng

The National Bank of Vietnam's 1966 series was printed by Thomas De La Rue during a period when South Vietnam's monetary system was under severe pressure from wartime inflation and the massive influx of U.S. military spending. The parallel black market for piasters — heavily manipulated by currency arbitrage schemes connected to the war economy — meant notes of this denomination circulated hard and fast, often passing through informal channels rather than banks.

De La Rue's contract work for South Vietnam across the 1960s produced several series; P#18 is among the more modestly secured, relying on a watermark alone without the thread or chemical features added to later issues.