Tough new lockdown restrictions on social gatherings across England are to be announced on Wednesday as Prime Minister Boris Johnson tries to control a spike in COVID-19 infections.
The Arena Racing Company (Arc), which operates the Doncaster track, has confirmed the remainder of the four-day meeting will be held without spectators.
"The race meeting will continue on a 'behind closed doors' basis, as per all other race meetings currently taking place in Britain," said Mark Spincer, the managing director of Arena's racing division.
"This pilot event represents a hugely important step not just for our business but for the whole of British racing as well as the sports and hospitality industries as a whole.
"We do, of course, fully understand and respect the decision and will be contacting all of our customers booked for the remaining three days as a matter of urgency."
The Town Moor horse racing venue welcomed around 2,500 fans to Wednesday's opening day amid uncertainty over new government rules.
It is the first crowd at a British horse racing event since the novel coronavirus lockdown, as part of a government pilot scheme for sporting events. (Reporting by Hardik Vyas in Bengaluru, editing by Pritha Sarkar)