The Swiss went to the polls Sunday to vote on controversial measures to decide citizenship for foreigners by secret ballot, dpa reported.
They are also being asked to approve health system reforms and restrictions on information handed out by the federal authorities.
A poll last month for the Swiss Broadcasting Corporation (SBC) indicated all three would be turned down but the right wing People's Party (UDC/SVP) has lobbied hard for a "yes" vote.
The party claims Switzerland is too soft on naturalization and wants communes to decide either by panel decisions, public assembly or secret ballot without the right of appeal.
The courts banned such measures five years ago following a number of controversial decisions which saw a vast majority of citizens of Balkan origin refused Swiss nationality in one commune.
Opponents insist the ballot box would be discriminatory with research suggesting it leads to more rejections.
The government and centre-right Radical Party have urged voters to reject the proposal, preferring the decision to be made by elected bodies with a right of appeal.
Swiss naturalization is already among the toughest procedures in Europe. Applicants have to be resident for 12 years before being eligible to apply compared with between four and ten years elsewhere.
Around 20 per cent of the population is made up of foreigners. In 2007, 45,042 applications were accepted, the highest number for 25 years but critics say the rate of acceptance is still lower than other European countries. It is 2.4 per cent compared with 4.1 per cent in the Netherlands, 4.9 per cent in France and 8.2 per cent in Sweden.
The result will be known later Sunday.