Hildesheim is a district (Landkreis) in Lower Saxony, Germany. It is bounded by (from the north and clockwise) the districts of Hanover, Peine, Wolfenbüttel, Goslar, Northeim, Holzminden and Hamelin-Pyrmont.
In 1885 the Prussian government established districts within the Province of Hanover. The present territory of the district was occupied by four districts: Hildesheim, Alfeld, Gronau and Marienburg. In 1932 the district of Gronau joined Alfeld, and the number of districts was reduced to three.
When the state of Lower Saxony was founded in 1946, the districts were reorganised: Hildesheim became an urban district, the remaining district of Hildesheim and Marienburg were merged to the new district of Hildesheim-Marienburg. The district of Alfeld remained in its former borders.
In 1974 the city of Hildesheim lost its status as an urban district and became part of the surrounding district, which was renamed to Hildesheim. The districts of Hildesheim and Alfeld were merged in 1977.