| Official Name: | Kfar Sir |
| Native Name: | كفرصير |
| Settlement Type: | Municipality |
| Pushpin Map: | Lebanon |
| Pushpin Label Position: | bottom |
| Pushpin Mapsize: | 300 |
| Pushpin Map Caption: | Location in Lebanon |
| Subdivision Type: | Country |
| Subdivision Type1: | Governorate |
| Subdivision Name1: | Nabatieh Governorate |
| Subdivision Type2: | District |
| Subdivision Name2: | Nabatieh District |
| Leader Title: | Mayor |
| Leader Title1: | Mayor |
| Unit Pref: | Imperial |
| Population Blank1 Title: | Ethnicities |
| Population Blank2 Title: | Religions |
| Timezone: | EET |
| Utc Offset: | +2 |
| Timezone Dst: | +3 |
| Coordinates: | 33.325°N 35.4008°W |
| Grid Position: | 118/154 L |
| Postal Code Type: | postal code |
| Area Code: | +961 - (07 - South Lebanon) |
Kfar Sir or Kfarsir (ar|كفرصير) is a municipality just north of the Litani River, in the Nabatieh District in southern Lebanon.
In the 1596 tax records, it was named as a village, Kafr Tir, in the Ottoman nahiya (subdistrict) of Sagif under the liwa' (district) of Safad, with a population of 58 households and 5 bachelors, all Muslim. The villagers paid a fixed tax-rate of 25 % on agricultural products, such as wheat, barley, olive trees, goats and beehives, in addition to "occasional revenues" and a press for olive oil or grape syrup; a total of 6,231 akçe.[1] [2]
In 2014 Muslims made up 99.36% of registered voters in Kfar Sir. 98.99% of the voters were Shiite Muslims.[3]