Polling is under way in the Pakistani city of Lahore for a keenly-watched by-election caused when the former prime minister stepped down in July.
The Supreme Court disqualified Nawaz Sharif from office over a ruling he was dishonest in a corruption inquiry.
His wife, Kulsoom Nawaz, is contesting the seat, but is currently in London for cancer treatment.
Instead her daughter Maryam Nawaz spearheaded the campaign for Mr Sharif’s PML-N party.
Sharif daughter seeks ‘people’s verdict’ in Pakistan poll
Mr Sharif has always denied any wrongdoing but the Supreme Court recently dismissed petitions seeking a review of that decision.
Long queues formed outside polling stations in the city on Sunday morning.
PML-N faces a strong challenge from the PTI party led by cricketer-turned-politician Imran Khan and the Pakistan People’s Party of Bilawal Bhutto Zardari.
Maryam Nawaz does not hold political office, but is one of the most high-profile figures in Pakistan and has taken centre stage in the lead-up to the by-election in her father’s former seat, constituency NA-120, in the family’s hometown.
During the by-election campaign Maryam Nawaz sought to portray the vote as the “people’s verdict” on her father’s disqualification.
In a recent BBC interview she said the issue had “galvanised his supporters” and that public sentiment is “very positive”.
Polls predict a PML-N victory, but it’s not clear whether their margin will increase or decrease. Fewer votes for the PML-N would allow political opponents to claim that even on the Sharif family’s home turf the corruption allegations are having an effect.
The election is being contested by all the major parties as well as two new Islamist opposition parties.
There are more than 320,000 voters taking part in the vote, which for the first time in Pakistan’s history will be conducted using Biometric Voter Verification Machines in some the constituency’s 220 polling stations, Dawn News reported.