Grein is an Upper Austrian municipality in the lower Mühlviertel in the district Perg. With an area of ​​18.42 square kilometers and with 2992 inhabitants (1 January 2016) is Grein size as the five tenth largest and based on the number of inhabitants the seventh largest community of the district. Grein is since 1491 the third oldest city of the Mühlviertel and capital of Strudengau. The city was the end of 2002 the site of the former District Court Grein, which was responsible for the ten municipalities of the judicial district Grein. Since the beginning of 2003 Grein belongs to the judicial district of Perg, the competent district court has since been held in the district capital Perg.