A conditioning regimen refers to the process of preparing a patient's body for a medical treatment or procedure, usually involving intense therapy or treatment. This can include chemotherapy, radiation therapy, or a combination of both, with the goal of reducing the risk of complications and improving the chances of a successful outcome. Conditioning regimens are often used in bone marrow or stem cell transplants, organ transplantation, and cancer treatments. The regimen may include drugs to suppress the immune system, eradicate cancer cells, or prepare the body to accept the new cells. The specific regimen will vary depending on the individual's medical condition and the nature of the treatment being received.