Epsom racecourse has announced that the Investec Derby and Oaks will start 30 minutes later this year and be run at 4.30pm.
Both Classics will still be run as the fifth race of seven, with the first race on both days now starting at 2pm.
Rupert Trevelyan, regional director - London, for Jockey Club Racecourses, said: "We have consulted all stakeholders in this process and consider this change will embellish our customers' experience of the Festival and the greatest flat race in the w3orld.
"We believe that from an attendance perspective, in particular for our sponsor and hospitality guests, this adjustment to our timings will enhance the overall enjoyment of their day. At this stage this is the extent of our changes to race times but we will review following the 2015 Investec Derby Festival.
"We are grateful to our colleagues at Channel 4 for accommodating our request."