Prime Minister Benjamin Netanyahu was undergoing medical checks in an Israeli hospital on Saturday but was in good condition, his office said, with no indications of a potential handover of power.
Netanyahu, at 73 the country's longest-serving leader, had complained of chest pain, was fully conscious en route to Sheba Hospital in Tel Hashomer town, and walked into the emergency room, Israel's Channel 12 TV said.
He was not undergoing sedation and no procedures were underway to declare him incapacitated, it added.
It was not immediately clear who might replace him in the event of an emergency succession.
First elected to top office in 1996 at the head of the conservative Likud party, Netanyahu has been both dynamic and polarizing, leading a free-market revolution in Israel while distrustful of internationally backed peacemaking with the Palestinians and talks to cap Iran's nuclear program.
He is in the grip of a domestic furor over his plan to overhaul the judiciary, which has set off unprecedented protests by Israelis worried for the future independence of the courts.
Netanyahu is himself no stranger to the docks, after being indicted in three corruption cases. He denies wrongdoing and has cast the trial as a politicized witch-hunt.
Tel Hashomer is close to the coastal town of Caesarea, where Netanyahu has a private residence.
In early October, he became ill during the Jewish fast of Yom Kippur and was briefly hospitalized. Israel has been in the grip of a weekend heatwave.
A brief statement from his office confirmed he was at Sheba and said he was in good condition undergoing medical assessment.
