They were the first to do so under a UN resolution authorising cross-border aid deliveries without the approval of President Bashir al Assad's government.
Amanda Pitt, spokeswoman for the UN Office for the Coordination of Humanitarian Affairs, said the trucks contained food, water purification tablets, and sanitation and shelter materials.
The convoy went through the Bab al-Salam crossing toward rebel-held areas but its destination was not known. She said: "It is the first convoy going into Syria through one of the four border crossings under the UN Security Council resolution."
The council unanimously approved a resolution on July 14 authorising cross-border delivery of aid to Syrians in rebel-held areas without government approval through four crossings - two in Turkey, one in Jordan and one in Iraq.
The UN humanitarian office has said that if security allows, aid could reach 2.9 million people through the four crossings.
The announcement of the first crossing coincided with UN Secretary-General Ban Ki-moon's monthly report to the Security Council on the worsening humanitarian situation in Syria. He denounced "indiscriminate" aerial bombings and shelling by government forces.