Golda Meir, the chain-smoking grandmother who led Israel through its bloodiest war and into the current search for peace in the Middle East, died yesterday in Jerusalem's Hadassah Hospital. She was 80.

In announcing her death, hospital officials disclosed one of the country's best-kept secrets: Mrs. Meir -- who served as prime minister from 1969 to 1974 -- had been fighting malignant lymphoma, a cancer of the blood, for more than 12 years.

Among the first world leaders to offer condolences was Egyptian President Anwar Sadat, whose army in 1973 Launched what was to be Israel's costliest war. He hailed Mrs. Meir as "an honest foe," and said she played an "undeniable role in starting" the current efforts for peace.

Former Secretary of State Henry Kissinger, whose shuttle diplomacy between Sadat and Mrs. Meir led to the first Israeli-Egyptian "disengagement" agreement, expressed sorrow at the death of a "dear friend" whose "consuming passion was peace for a people that had never known it."

Israeli Prime Minister Menachem Begin, who received news of Mrs. Meir's death while in Oslo, Norway, to accept his share of the Nobel Peace Prize, announced through a spokesman that he would not have any comment until today because of the Jewish Sabbath.

But Israeli President Yitzhak Navaron, in a statement broadcast over the government radio, declared: "This is mourning for all the people of Israel, both in Israel and the diaspora."

Sadness was also expressed by many in the United States, for Mrs. Meir -- who was born in Kiev, Russia, on May 3, 1898 -- had emigrated to the United States with her family in 1906, and taught school in Milwaukee for several years before leaving for Palestine.

President Carter took note yesterday of the "special love and affection" felt for Mrs. Meir. Praising her as embodying "the best in the Israeli spirit," Carter said: "On the occasion of her death, it is fitting to note that the nation of Israel to which she dedicated her life is strong and free today."

A hospital spokesman said Mrs. Meir's son, daughter, and sister, Florence Stern of Bridgeport, Conn., were at her bedside when she died at 4:28 p.m. yesterday of viral hepatitis resulting from the blood disease.

Mrs. Meir had been in and out of the hospital several times in recent months -- the last time Oct. 29 when it was reported that she was suffering from back trouble.

Doctors disclosed yesterday that the cancer that led to her death had been detected in the late 1960s, and that she had been treated for it -- first with radiotherapy and later chemotherapy -- even as she was leading Israel through the October 1973 war.

But Mrs. Meier -- who was once described by Israel's crusty first prime minister, David Ben-Gurion, as "the only man in my Cabinet" -- would not permit disclosure of her illness, even at the end.

Ironically, death came to Mrs. Meir with Israel apparently on the brink of the peace with Egypt that she had sought for almost six decades.

Someday peace will come, she said in 1974, "but I doubt that I will still be here to see it."

Golda undoubtedly came closer than she had expected.