Lymph nodes on the left and right sides are not the same size, which may be related to lymphadenitis, lymph node tumor and other reasons. 1. Lymphadenitis: under normal circumstances, lymph nodes are not accessible, when infected by bacteria or viruses, the inflammation stimulates the normal lymph nodes on one side, causing lymphadenitis, which can lead to inconsistency of lymph nodes on both sides, and can be dispersed by itself after controlling the inflammation. 2. Lymph node tumors: such as lymphoma, malignant tumors originated from lymph nodes and extra-nodal lymphatic tissues, manifested as painless lymph node enlargement, local lumps and so on. There are also lymphatic metastasis of malignant tumors, resulting in different size of lymph nodes on both sides. If the left and right lymph nodes are not the same size for a long time, there may be other reasons. It is recommended to go to the hospital in time, complete the examination under the guidance of a professional physician, and carry out relevant treatment after clarifying the cause of the disease, so as to avoid delaying the condition.