The strikes have killed 464 Islamic State group fighters, 57 militants from al-Qaeda affiliate al-Nusra Front and 32 civilians, the Britain-based Syrian Observatory for Human Rights said.
Among the civilians killed were six children and five women, said the Observatory, which relies on a wide network of sources inside Syria.
The US-led coalition against the Islamic State launched air strikes against IS on September 23, expanding a previous aerial campaign launched against the group in Iraq in August.