The East Lothian course offered free entry as part of a month long initiative by Racing for Change involving 25 UK racecourses.
All the freebies have been snapped up, but race goers turning up on the day will be able to buy special tickets priced £10 instead of the normal £21 admission price.
Musselburgh Racecourse commercial manager, Sarah Montgomery, said: “The free offer has been a great success and we are sure of a bumper crowd with a superb atmosphere on our first day of our flat season.
“We recognise not everyone may have been aware of the free offer and some race goers will be travelling a distance to Musselburgh so there will be limited tickets on sale on the day at the reduced price of £10.”
The Racing for Change promotion follows a similar programme last year which brought in an additional 40,000 visitors to the races. This time 28 fixtures, spread throughout April, will offer free entry at some of the UK’s leading courses including, Musselburgh and Perth (first 500) in Scotland, and Ascot, Epsom Downs, Newbury, Newmarket and Sandown Park.