Jihadists on Friday withdrew from Saraqeb, their last bastion in the Syrian province of Idlib, five days into a major battle in the town against local rebels, a monitor said.
In the region of Aleppo, rebels also made advances except in Jarabolos on the border with Turkey, which the Islamic State of Iraq and the Levant (ISIL) seized, said the Syrian Observatory for Human Rights.
Rami Abdel Rahman of the Syrian Observatory for Human Rights said "members of the Islamic State of Iraq and the Levant withdrew at dawn today from Saraqeb to Sermin."
"ISIL withdrew after their situation there became very hard... and after they were besieged by Islamist and moderate rebel groups from all sides," said Abdel Rahman.
Their retreat comes two weeks into a major rebel offensive against the jihadist ISIL.
While rebels and jihadists were once allied in the fight against President Bashar al-Assad, ISIL's quest for hegemony and its horrific abuses against the local population and opposition has turned rebels -- including other Islamists -- against them.
Abu Leila, a rebel from Idlib who is opposed to both Assad and ISIL, told AFP that the jihadists "withdrew to save themselves".
Dozens of ISIL fighters were killed or injured in the fighting for Saraqeb, where a major battle pitting rebels and jihadists broke out on Monday.
Saraqeb was once a key source of inspiration for moderate activists using art and other peaceful means to protest Assad's regime.
Long out of regime control, it fell to ISIL last month.
The battle for Saraqeb is part of a wider rebel offensive against ISIL in several parts of Syria, which in two weeks has killed nearly 1,100 people, most of them fighters on both sides.
In Aleppo, two ISIL suicide bombers detonated themselves near checkpoints manned by rival rebels, said the Aleppo Media Centre, a grassroots network of citizen journalists.
ISIL has staged some two dozen suicide attacks in the past two weeks targeting rebel positions. Scores of rebels and civilians have died as a result.
In Jarabolos, on Aleppo province's border with Turkey, ISIL "took total control... after fierce fighting against rebels," said the Observatory.
Abdel Rahman also said ISIL summarily executed several rebels captured during the fighting.
But in another part of the province, rebels pushed out ISIL fighters from an army post they had turned into a jihadist bastion.
Rebels fighting ISIL have described progress in their war against the jihadist as "mixed."
"In some areas, there is good progress. In others, the situation is bad," said one Islamic Front fighter, whose alliance is among the key groups battling both ISIL and Assad's regime.
On another front, Assad loyalists shelled Madira, northeast of Damascus, killing 11 people, said the Observatory.
Syria's nearly three-year war has killed more than 130,000 people and forced millions of others to flee their homes.