In the shadow of the civil war that took place in Spain, the year 1937 caused very active and unsettling incidents in the Mediterranean and its surroundings. Some submarines, whose identity seems to be unknown torpedoed and sank some merchant ships in and around the Mediterranean. These incidents, which shook the stability and security of the region, had a close relationship with the civil war in Spain. Germany and Italy, which constituted the Axis group in World War II, supported General Franco in this civil war. They provided him with weapons and equipment. Moreover, İtaly provided even soldiers to him. On the other hand, Soviet Union supported Franco's rivals, the Republicans. As for Britain and France, these two states were opposed to Franco's seizure of power in Spain, although they were not openly party to the incident. In addition, Britain and France were also concerned about the spread of the war to Europe. Terrorist attacks began in the Mediterranean by unidentified submarines against the ships of the states supporting the opposition to Franco. Merchant ships were torpedoed and sunk by these submarines. Others faced conversion and detention. The aforementioned incidents were also observed with concern by the states in the region. Thereupon, with the initiative of France and Britain, an international conference was held to prevent these maritime piracy activities in the Mediterranean. On September 10, 1937, the Nyon Conference, which was held in Nyon, Switzerland, with the participation of nine countries, namely France, Britain, Bulgaria, Egypt, Romania, Soviet Union, Turkey, Yugoslavia, and Greece, began its work. These works were completed in a short time and The Nyon Agreement was signed on September 14, 1937. The Nyon Conference was very important because of the contributions of the nine states that signed the agreement to ensure the security of the Mediterranean by coming together in cooperation and solidarity. In this study, the process leading to the Nyon Conference, the convening of the Conference and the contribution of The Nyon Agreement, which was signed at the end of the negotiations, to the security of the Mediterranean were examined.