About 90% of the ailments nowadays are thought to be due to reactive oxygen species(ROS), and thus the ROS-scavenging effect of the placenta may be effective in these conditions. By controlling the autonomic system, endocrine system, and stimulation of the immune system, the placenta has effects to improve various kinds of illnesses. However, there has not been a sufficient amount of data from systematic research on the therapeutic effectiveness of the placenta, and more attention from physicians and scientists is expected on this field to provide evidence for its usefulness on many intractable diseases, chronic diseases, and cancer. Besides, the placenta can play a role in anti-aging, rejuvenation, and esthetics without significant side effects. Thorough evaluation of the efficacy and the safety is needed to make placenta a promising therapeutic agent.