The Britain-based Syrian Observatory for Human Rights said the extremist group had managed to seize the six villages north of the city of Aleppo, and not far from the border with Turkey.
Fighting was ongoing for control of another village in the area, Arshaf, the group said.
The Observatory said the group took the areas "after fierce clashes with rebels and militant battalions that remained in the area after Al-Nusra Front and other militant battalions withdrew at the end of July".
Al-Nusra Front, which is Al-Qaeda's Syrian branch, joined moderate and rebel groups in a coalition that began fighting the Islamic State in January.
But in recent weeks, Al-Nusra has also fought other rebel groups, further complicating the status of the armed opposition in Syria.
The Observatory said the IS capture of the villages was a strategic prize, because it would open the way for the group to attack the towns of Marea and Azaz.
Marea is a stronghold of the Islamic Front, a coalition of Islamist groups that is among those fighting against IS.
Azaz sits next to the border crossing with Turkey, which would be a valuable asset to IS as it seeks to expand its self-declared "caliphate" in the territory it holds in Syria and neighbouring Iraq.
The Islamic State emerged from Al-Qaeda's one-time branch in Iraq, and initially fought alongside Syria's opposition, including moderate rebels and Al-Nusra fighters.
But its abuses against civilians and rival fighters, as well as its bid to dominate control of captured territory, sparked a backlash.
The group was pushed out of much of the territory it held in Aleppo province by the coalition of moderate and Islamist rebels that turned against it in January.
But it has been able to recapture some of that lost ground, and is advancing in Aleppo while consolidating its hold in its stronghold of Raqa province and sweeping forward in Iraq.
The Observatory said its advances in Aleppo had been assisted by the decision of the militant Dawud Brigade to pledge allegiance to the Islamic State.
More than 170,000 people have been killed in Syria since the conflict began there in March 2011.
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An army of jehadee against jehaad has recently formed in Philipines with a determination to root out jehaadi mentality through which change is expected by the supporters of PTI in the system , This millitant movement is against millitants may not remain confined there but can be a source of inspiration for many people in Pakistan . Those who were against the Nawaz are now supporting him for a common cause .
It's a development that deserves the attention of entire world community .
Now it may be the desired change is taking place in the muslim community ,
Nice picture. This is what will be left when an Islamic State is established.