
The spa business last year contributed more than Bt13 billion in terms of tourism income to the country.
Association president Andrew Jacka said annual sales would grow little for the next three years.
"As a result of fewer tourist arrivals, the operators are bound to see a fall," said Jacka, noting that according to the association's data about 90 per cent of spa customers were foreigners.
He said the economic slowdown and internal political turbulence were the main drags on business growth from double to single digits.
All the association's 320 members are suffering from the economic crisis. Recently it announced that sales would go down Bt1.1 billion from December, 2008 to June, 2009.