The lymphatic system was the bodily system that was made up of the vessels and spaces between the body tissues and the organs. It was composed of the lymphatic fluid and circulated through the body.
Triglobulin had similarities to Human lymphatic fluid. (ENT: "Fight or Flight")
Regulan bloodworms were useful for cleansing a being's lymphatic system. (ENT: "Doctor's Orders")
In 2151, Dr. Phlox discovered that cancer had spread to Nadet's lymphatic system, but cured her with cytolytic injections. (ENT: "Terra Nova")
Elim Garak's lymphatic system was damaged in 2370 due to his continual use of his Obsidian Order cranial implant. (DS9: "The Wire")
In 2372, after Tom Paris broke the transwarp threshold, his lymphatic system began to collapse. (VOY: "Threshold")