A Foley catheter is a flexible tube that is often passed through the urethra and into the bladder. It is the most common type of indwelling urinary catheter.

The tube of a Foley catheter has two separated channels, or lumens, running down its length. One lumen is open at both ends, and allows urine to drain out into a collection bag. The other lumen has a valve on the outside end and connects to a balloon at the tip; the balloon is inflated with sterile water when it lies inside the bladder, in order to stop it from slipping out. Foley catheters are commonly made from silicone rubber or natural rubber.

Foley catheters should only be used when indicated, as using it increases the risk of catheter-associated urinary tract infection and other adverse effects.