The electorate of almost 350,000 is being called to choose 40 deputies, with Sunnis making up most of the 266 candidates.
The polls are being contested without a compromise in sight between authorities in the Sunni-ruled monarchy and the opposition.
Al-Wefaq, the main opposition group, has dismissed the electoral process as a "farce" and warned that failure by the kingdom's rulers to loosen their grip on power could trigger a surge in violence.
The political rivals have struggled to bury their differences through a so-called "national dialogue" that fell apart despite several rounds of negotiations.
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Polling stations opened at 8:00 am (0500 GMT) and are due to close at 8:00 pm. Municipal elections are being held at the same time.
The opposition boycott means voter turnout will be a key marker of the validity of the vote.
Al-Wefaq chief Sheikh Ali Salman has predicted a maximum turnout of 30 per cent, saying the boycott stems from "the people's demand for democratic reforms".