This chapter reviews the potential of 222 nm UV-C light as a method with safety and germicidal effect for sterilization in medical and clinical environments. Over the past decade, attention was focused on 222 nm UV-C due to its ability to inactivate microorganisms without causing harm to human tissue. This is because 222 nm UV-C has low penetration, making it safer compared to conventional UV-C wavelengths like 254 nm UV-C, which are harmful to skin and eyes. Extensive research has accumulated data supporting both the safety and germicidal efficacy of 222 nm UV-C. Clinical trials and basic studies have demonstrated its ability to kill a wide range of pathogens, including antibiotic-resistant bacteria, while maintaining safety for human tissues such as skin, wounds, and eyes. The American Conference of Governmental Industrial Hygienists (ACGIH) has revised its threshold limit values (TLV) for 222 nm UV-C, further confirming the reliability of these findings. In medical applications, 222 nm UV-C is supposed to have both direct irradiation of patients to prevent surgical site infections (SSI) and sterilization of medical environments like operating rooms. While many studies have focused on environmental sterilization, further clinical trials are needed to validate its safety for direct patient use. It is expected that in the near future, 222 nm UV-C will become a well-established method for safe and effective disinfection, addressing both hospital-acquired infections and broader public health concerns.