A clothes line, also spelt clothesline and also known as a washing line, is a device for hanging clothes on for the purpose of drying them. It is any type of rope, cord, or twine that has been stretched between two points (e.g. two sticks), outside or indoors, above the level of the ground. Clothing that has recently been washed is hung along the line to dry, using clothes pegs or clothespins. Washing lines are attached either from a post or a wall, and are frequently located in back gardens, or on balconies. Longer washing lines often have props holding up sections in the middle due to the weight of the usually wet clothing.

More elaborate rotary washing lines save space and are typically retractable and square or triangular in shape, with multiple lines being used (such as the Hills Hoist from Australia). Some can be folded up when not in use.

In Scotland, many tenement buildings have a "drying green", which is a communal area predominantly used for clothes lines – it may also be used as a recreational space - as well as a clothes horse connected to a pulley system inside which can be used in the frequently cold winter weather.