The Potrosac association filed a collective suit against the banks, demanding that the hard-currency clause in Swiss francs be abolished and substituted with a clause in euros, lawyer Nicole Kwiatkowski told AFP.
However Zagreb commercial court judge Radovan Dobronic ordered the plaintiff to provide more details on each of the eight banks' policies within the next 60 days.
Around 125,000 people in Croatia have taken out loans denominated in Swiss francs, 60 percent of which were housing loans.
Due to a rise in the value of the Swiss franc and changes in interest rates, some of their loan installments have even doubled in the last few years.
Most of the banks in Croatia stopped granting loans in Swiss francs in 2008.
Croatia's central bank (HNB) monetary policy is based on maintaining fluctuations of the local currency kuna exchange rate against the euro within a stable range.
However the exchange rate between kuna and Swiss franc depends on fluctuations of the exchange rate between euro and the Swiss franc.
Local media estimated that the trial could last up to two years.