The Red Crescent said that 10 trucks of aid including blankets and hygiene supplies provided by the United Nations had entered the besieged rebel-held town of Moadamiyet al-Sham southwest of Damascus.
Red Crescent official Muhannad al-Asadi said it was "the first delivery since the beginning of the truce" and that another 41 trucks were set to enter the town on Monday.
The trucks were carrying sanitary pads, soap, laundry detergent and blankets provided by the United Nations' refugee and child agencies, he said.
The truce, which was in its third day on Monday, is meant to open the way for aid to the more than 480,000 Syrians living in areas besieged by government forces, rebels or jihadists.
UN humanitarian coordinator Yacoub El Hillo said the world body hoped to take advantage of the relative calm to distribute supplies to 154,000 people living in besieged areas over the next five days.