Seventeen women and 54 men are competing for the 12 seats on the board of the Chamber of Commerce in the Saudi business capital, Jeddah.
Voting takes place over four days – for the female candidates voting was on Saturday and Sunday, while voting for the men is on Monday and Tuesday.
The vote is seen by liberals as a sign of progress.
BBC Middle East analyst Roger Hardy says the election is of great symbolic importance in a conservative country where women’s lives are restricted in many ways.
Our correspondent says women’s activists are trying to put a brave face on the fact that the turnout at the weekend was low.
By Saudi standards, the chambers of commerce are modern, liberal institutions.
They have long prided themselves on the fact that they conduct often strongly contested internal elections.
But in general, voting is still a novelty in the kingdom – and for the many Saudis who want reform, progress has been painfully slow, our correspondent says.
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