Israeli Prime Minister Benjamin Netanyahu claims victory
Two exit polls predicted that right-wing parties allied to Mr Netanyahu were more likely to be able to form a governing coalition.
The centrist Blue and White alliance of former military chief Benny Gantz was projected to win 36 or 37 seats, with the Likud party of Prime Minister Benjamin Netanyahu taking 33 to 36.
Both men have claimed victory.
But a third exit poll predicted that the bloc would be tied with centre-left parties allied to Mr Gantz.
"We won! The Israeli public has had its say!" Blue and White said in a statement. "These elections have a clear winner and a clear loser."
But at his party's election headquarters in Tel Aviv, Mr Netanyahu was also celebrating.
"It is a night of colossal victory," he said. "I'm very touched that, for the fifth time, the people of Israel have believed in me."
No party has ever won a majority in Israel's 120-seat parliament, the Knesset, and the country has always had coalition governments.
BBC News