Darb as-Sim () is a municipality in the Sidon District of the South Governorate in Lebanon.
In 1875 Victor Guérin visited and described it: "I arrive at the village of Derb es-Sin, also known as Deir es-Sin. Inhabited by 300 Maronites, it must have succeeded an ancient settlement. A few plantations of mulberry, orange, and fig trees are nearby."
In 2014, Christians made up 98.14% of registered voters in Darb as-Sim. 79.76% of the voters were Maronite Catholics.