The Protocol for the Prohibition of the Use in War of Asphyxiating, Poisonous or other Gases, and of Bacteriological Methods of Warfare, usually called the Geneva Protocol, is a treaty prohibiting the first use of chemical and biological weapons. It was signed at Geneva on June 17, 1925 and entered into force on February 8, 1928. It was registered in League of Nations Treaty Series on September 7, 1929.

It prohibits the use of chemical weapons and biological weapons, but has nothing to say about production, storage or transfer. Later treaties did cover these aspects—the 1972 Biological Weapons Convention and the 1993 Chemical Weapons Convention.

A number of countries submitted reservations when becoming parties to the Geneva Protocol, declaring that they only regarded the non-use obligations as applying to other parties and that these obligations would cease to apply if the prohibited weapons were used against them.

Chemical weapons were used by the German Empire in Ypres, Kingdom of Belgium in 1915, when chlorine gas was released. The Treaty of Versailles included some provisions that banned Germany from either manufacturing or importing chemical weapons. Similar treaties banned the First Austrian Republic, the Kingdom of Bulgaria, and the Kingdom of Hungary from chemical weapons.