In addition to municipal charters, general town bylaws (Wilkühr) were among the most important documents regulating life in a town. They were collections of rules which governed the conduct of local communities. The Wilkühr was drafted by the local inhabitants upon the consent of the authorities. The article describes the unknown town bylaws of Giżycko (formerly Lötzen) which were introduced between 1669 and 1723. A copy dating back to the 17th/18th centuries has survived to this day and is used by the court in Giżycko. The document contains 105 articles which deal with various municipal issues. They offered protection to different religious groups and established their right to celebrate religious holidays and hold church ceremonies. They guaranteed the dignity of the noble classes in their dealings with the local authorities, clergy and townsfolk. Selected articles regulated local governance, citizenship acquisition, distribution of responsibilities among members of the local community and organizational matters in the town. The Wilkühr also addressed trade issues and introduced fire fighting rules. It dealt with land holdings, meadows, horse pastures, municipal forests and livestock keeping. The document detailed the rights and obligations of servants and hired workers, and it set rules for the management of fisheries. Unlike other collections of common bylaws, the Wilkühr did not regulate the activities of local craftsmen and breweries, and its general focus was on land, meadows and pastures. The discussed document offers valuable insights into the problems faced by the inhabitants and authorities of modern towns in the Duchy of Prussia.