The Palestinian Election Commission says the Islamic militant group Hamas has won 76 of the 132 seats in the Palestinian parliament.
The Fatah party won 43 seats in Wednesday's elections, in which more than 77 percent of eligible Palestinians voted.
Hamas officials say they want to start talks on the shape of a new government. But Fatah party leaders say they would not join a coalition with Hamas.
Officials expect Palestinian Authority President Mahmoud Abbas to soon ask Hamas to form a government. Palestinian Prime Minister Ahmed Qureia and his cabinet resigned earlier on Thursday.
Hamas supporters stormed the Palestinian parliament in Ramallah and raised the group's flag over the building.
Hamas has carried out suicide attacks on Israelis and is branded a terrorist organization by Israel and the United States. The Bush administration has called on Hamas to disarm and end its quest to destroy the Jewish state.