A nipple clamp is a clamp used to stimulate the nipples by applying varying degrees of pressure. They are often used in certain BDSM activities, on both men and women.

The main types of nipple clamp are the clover clamp and the tweezer clamp. The common household clothes-pin is also popular. However, any device that can be used to apply direct pressure can be used.

Weights may be hung from the clamps to increase the force on the nipples. This also discourages the clamped person from moving suddenly (for example, jumping when spanked or caned), since this would make the weights swing and increase the pain.

A single tweezer-style nipple clamp on a chain, adjustable by turning the metal rod

Tweezer clamps consist of two short lengths of metal, no more than 5-10 cm (2-4 in) in length. The ends are curved slightly to improve their ability to grip the nipple. Typically, they have a small 1 cm rubber sheath over this end to protect the nipple from damage. A small ring wraps around the two pieces of metal and is used to adjust the tension. The user places the two sides of the metal head either side of the nipple, then by sliding the ring along the clamp shaft towards the nipple, causes the two halves to close tighter together. Tension can thus be adjusted depending on the location of the ring - the closer the ring is along the shaft toward the nipple, the tighter the clamp.

The clover clamp, also referred to as a "butterfly clamp" is of Japanese design, and has the ability to provide increasing tension if pulled on. The clamp itself is flat, but about 10 cm by 5 cm in size. Using spring tension, the clamp is applied to the nipple and the tension of its spring holds the clamp in place. This clamp usually provides a very high pain level, and is usually only used by more advanced users. To increase tension on the nipples, small weights such as fishing line sinkers can be attached to the ends of the clamp. As increased pulling tension is applied to the clamp, it will cause the jaws of the clamp to close tighter depending on the amount of pull pressure. Another method is to use the clamps to keep a person in one place. If cord is tied from the clamp to a fixed place, the wearer of the clamps cannot move away because the clamps will tighten as they try to move. Eventually the clamps would be pulled off the nipples, but not before considerable pain and discomfort is felt.