Demonstrators in Reyjavik have called on the government to resign and for banks to be more open about Iceland's financial crisis.
Iceland's economy has been brought to its knees by the global banking crisis and the local currency, the krona, is down 40% in value since the beginning of the year.
Many Icelanders have lost large sums of money.
Between 3,000 to 4,000 protesters turned out on the fourth consecutive Saturday of demonstrations. Their numbers are growing each week.
Details are still being finalised of an agreement with the International Monetary Fund for a loan of $US2 billion.
Iceland is looking for an additional $US4 billion.