Online payment service PayPal has released data that shows more than 12 million of its users pay for Facebook games every month.
In a report on VentureBeat, Paypal also revealed that its users favoured World of WarCraft, Final Fantasy, Bejeweled, and FarmVille.
"In massively multiplayer online games, the number of paying gamers keeps going up," said Carey Kolaja, Paypal's senior director of emerging opportunities.
"The perception about digital goods is that they lead to micro transactions, which are small. But the average purchase for a paying user is in the mid-20s (in dollars). It is on a positive trajectory."
Most MMO players, 54 per cent, spend between $10 to $50 on virtual currency. 27 per cent spend more than that, while just 19 per cent stick to smaller purchases of under $10.
In social games just 9 per cent spend more than $50, while 22 per cent of "casual web site games" players send over the $50 mark.
Paypal also reveals that more than 40 per cent of adults are playing games online, and claims that 70 per cent of gamers use PayPal.
Paypal launched in 1998 and now has over 100 million users and $1 billion in quarterly revenue.