 After her commissioning, Medusa was assigned to the fleet reconnaissance forces. In 1905, she was assigned to the Cruiser Division, alongside her sisters Ariadne and Amazone and the armored cruiser Prinz Heinrich. She served in the fleet scout role up to the outbreak of World War I in August 1914, at which point she was employed as a coastal defense vessel. In 1917, she had four of her guns removed, and she was used as an auxiliary ship for the old ironclad König Wilhelm, which was being used as a training ship for naval cadets.
