杀菌（Sterilization），又称作灭菌，与消毒（disinfection）近似，但更追求移除或消灭物体表面、液体、药物、培养介质上的任何形式微生物及传播性病原体（如真菌、细菌、病毒、芽孢等）。适当地使用高温、化学品、放射线、高压及过滤进程可以有效达到杀菌效果。

杀菌也包含将感染性蛋白（如朊毒体）破坏。

杀菌通常都是用于一切会接触病人伤口或体内的仪器，确保没有微生物感染身体组织，例如一些外科手术或身体检查所使用的医疗仪器。

Sterilization (or sterilisation) is a term referring to any process that eliminates (removes) or kills (deactivates) all forms of life and other biological agents (such as viruses which some do not consider to be alive but are biological pathogens nonetheless), excluding prions which cannot be killed, including transmissible agents (such as fungi, bacteria, viruses, prions, spore forms,unicellular eukaryotic organisms such as Plasmodium, etc.) present in a specified region, such as a surface, a volume of fluid, medication, or in a compound such as biological culture media. Sterilization can be achieved with one or more of the following: heat, chemicals, irradiation, high pressure, and filtration. Sterilization is distinct from disinfection, sanitization, and pasteurization in that sterilization kills, deactivates, or eliminates all forms of life and other biological agents.