Israel's army reopened the border crossing between Egypt and the Gaza Strip on Friday, allowing 1,500 Palestinians to head home after being stuck on the Egyptian side for three weeks.
Small children and elderly people were among travellers stranded in desert heat and unsanitary conditions in the Rafah terminal. Washington, Israel's close ally, had expressed concern about the Palestinians' plight.
The first busload of exhausted travellers entered Gaza just after 10 am (0700 GMT), the first passage since July 18.
Another 2,000 Palestinians were following them after waiting at hotels in Egypt's northern Sinai region, officials said.
Israel's army shut the crossing - one of many such clampdowns imposed during an almost four-year-old Palestinian revolt - saying it was checking a report that militants wanted to blow up the terminal from a tunnel to be burrowed underneath.
It is in a dusty area, blazing hot in summer, where Israeli forces regularly play a bloody game of cat-and-mouse with militants who dig tunnels to smuggle munitions into Gaza.
Israel occupied Gaza in the 1967 Middle East war and has controlled its borders since. Israeli Prime Minister Ariel Sharon plans to evacuate Jewish settlers from Gaza in 2005 but keep the poor, overcrowded territory encircled afterwards.
The Rafah crossing, the sole exit to the Arab world for Gaza's 1.3 million Palestinians, was reopened a day after White House envoy Elliot Abrams had talks with Sharon in Jerusalem.
Many of the Palestinian travellers had been returning home from treatment abroad for serious ailments and they relied on aid from the Egyptian Red Crescent to cope with the wait.
Some of them complained of coming down with skin infections from deteriorating health conditions and witnesses said three women had suffered miscarriages.
Families camped in communal tents with mats at the crossing, enduring heat exceeding 35 degrees Celsius (95 degrees Fahrenheit).
"I was coming home from four months of chemotherapy in Cairo when Rafah suddenly closed. I've been through hell here, especially since I was already weak from my chemotherapy," said Karina Mohammedali, 50, as she crossed into Gaza.
"My hands swelled where they injected me and I had stomach upsets and was afraid to go to the bathroom because it was dirty and very crowded. Thank God my imprisonment is over," she said.
"I hope this international passage will remain open and that Israel will not repeat such inhumane measures that created this miserable situation," Palestinian cabinet minister Saeb Erekat told Reuters in the West Bank city of Ramallah.
Egypt's MENA news agency quoted Salim Abu Safia, the Palestinian border post chief at Rafah, as saying the Israelis had informed him Palestinian travel the other way, into Egypt, could resume on Monday once the backlog from Egypt was cleared.