A nasogastric tube (NG tube) is a plastic tube, inserted into a nostril through the nose, into the throat, down the oesophagus and into the stomach.

During the tube's insertion, great care must be taken to ensure that it has not entered the trachea. For verification purposes, air is injected into the tube, and with a stethoscope it is possible to detect the passage of air into the lungs or into the stomach. Another method is to aspire with a syringe; the tube is properly seated in the stomach if greenish liquid is returned.

Nasogastric tubes can be used to drain the stomach's contents, particularly if the beneficiary is suffering from a bowel obstruction, toxicity (such as an overdose), nausea or is preparing for a pressing surgery under anaesthesia. If the tube is used for continuous drainage, it is usually appended to a collector bag placed below the level of the beneficiary's stomach; gravity empties the stomach's contents. It can also be appended to a suction system, however this method is often restricted to emergency situations, as the constant suction can easily damage the stomach's mucous membrane, the mucosa.

A nasogastric tube can be used to extract a sample of gastric liquid for analysis. If this is the case, a syringe is used for aspiration.

They are also used for feeding and for administrating drugs. For drugs and for minimal quantities of liquid a syringe is once again used for the injection into the tube. For continuous feeding, a gravity based system is employed, with the solution placed higher than the beneficiary's stomach. If accrued supervision is required for the feeding, the tube is often connected to an electronic pump which can control and measure the beneficiary's intake and signal any interruption in the feeding.

In Britain, tubes were used for force feeding as a result of the Cat and Mouse Act.