UK betting firm Ladbrokes has seen revenue fall by 6% in the first four months of 2010.
And it said that amounts staked by customers across its UK stores had dropped by 10%.
Profits from gaming machines were also lower after VAT reverted to 17.5% in January.
Chief executive Richard Glynn said the economic climate remained "challenging" and the strength of UK consumer confidence was "difficult to gauge."
Ladbrokes said it had seen a surge of bets on the outcome of the general election, but that the outcome of a hung parliament had led to a large number of payouts.
The bookies said it also took a hit after punters' favourite Tony McCoy rode a Grand National winner for the first time in 15 attempts, although it added it had done well at the Cheltenham festival, where several of the favourites floundered.
"It's been a very mixed period, but at the end of the day, that's the nature of the business," said finance director Brian Wallace.
Mr Wallace added he expected more than £500m to be wagered on next month's World Cup.