| Native Name: | Isarkreis |
| Common Name: | Isar District |
| Subdivision: | Regierungsbezirk |
| Nation: | the Kingdom of Bavaria |
| Capital: | Munich |
| Year Start: | 1806 |
| Year End: | 1837 |
| Image Map Caption: | Districts of Bavaria, including Tyrol, in 1808 |
| S1: | Upper Bavaria |
| Flag S1: | DEU Oberbayern COA.svg |
The Isarkreis (German: Isar District) was one of the 15 administrative districts (German: Bezirke or Regierungsbezirke) of the Kingdom of Bavaria between 1806 and 1837. It is named after its main river, the Isar. It was the predecessor of the Regierungsbezirk Oberbayern (Administrative District of Upper Bavaria).
In the years between 1806 and 1808 the Kingdom of Bavaria was divided into 15 districts. Their names were taken from their main rivers. The Isarkreis, with Munich as its capital, was initially composed of 14 rural divisions and, since 1809, of the independent cities of Munich and Landsberg. In 1810, the Isarkreis was expanded. In 1817, there was another reshuffle; some areas were added and other ones given to the Upper Danube District (Oberdonaukreis). In another territorial reorganization initiated by King Ludwig I on 29 November 1837, the Isarkreis was renamed Upper Bavaria (Oberbayern).
The district was divided in the following judicial districts (Landgerichte = LG), according to the original borders of the districts of the former territories (Herrschaftsgerichte = HG):