It is not yet known where in Ireland the winning ticket for last night's EuroMillions jackpot was sold.
The winning ticket, worth €38.9 million, had the numbers 04, 08, 22, 23, and 48, with the lucky stars 01 and 12.
The National Lottery is appealing for everyone to check their tickets.
A spokesperson said: "At this stage we don't know if it's a single winner or a syndicate."
She added: "We advise anybody who has this ticket to keep it safe until they can get into the National Lottery office next week to make their claim. This is a valuable piece of paper."
The win makes it a record year for Irish EuroMillions jackpots.
It is third EuroMillions jackpot won in Ireland this year and the 12th since EuroMillions began in 2004.
A Dublin work syndicate claimed a €88.5 million EuroMillions jackpot in January, while a west of Ireland syndicate scooped almost €29 million in July.