The lymphatic system is usually considered part of the circulatory system.
"The lymphatic system consists of organs, ducts, and nodes. It transports a watery clear fluid called lymph. This fluid distributes immune cells and other factors throughout the body. It also interacts with the blood circulatory system to drain fluid from cells and tissues."
The main function of the lymphatic system is to defend the body against diseases, absorb fats from the intestines and transport them to the blood, and to collect and return interstitial fluid, including plasma protein to the blood.
The lymph organs are comprised of bone marrow, lymph nodes, spleen, and thymus.