Swiss voters are deciding whether to introduce new laws that would limit executive pay to 12 times that of the lowest paid.
It is the second time this year that they have been balloted on the issue.
In March they backed strict limits on bonuses and golden handshakes.
The new rules would give Switzerland the world’s toughest pay rules and some of the lowest executive salaries – which business leaders say would limit foreign investment.
The government is also opposed to the move.
There is widespread public anger at revelations that some of Switzerland’s chief executives are earning more than 200 times what their employees take home.
Some Swiss have been further irritated that these high levels of pay are being given to executives whose firms have been cutting jobs.
Switzerland’s system of democracy means citizens can call nationwide votes on issues that concern them.
Recent opinion polls show a slight majority against the proposal.
The result is expected to be announced this afternoon.