Hernals is the 17th district of Vienna, Austria (German: 17. Bezirk, Hernals). Hernals is in northwest Vienna.
The district of Hernals stretches out along the canals of the Als River west of Vienna between the Wienerwald (Vienna Forest) and the Gürtel (a main street around inner Vienna). The Als is the second-longest stream (the longest is the Wien River) to flow from the Wienerwald into the Danube.
The highest point, at 464 meters, is Heuberg. The original Vororte of Hernals, Dornbach, and Neuwaldegg were annexed in 1892 and form the heart of the 17th district. The houses in the central areas were built around the turn of the 19th–20th centuries during the Gründerzeit. Further out, the original farmer houses remain, often with gardens and villas added on. Farmland composes about 29.7% of the land area of the district, and transportation support buildings compose about 10.3% of the area.
With about 59.6% of the area populated with greenery, Hernals is one of the greenest districts in Vienna, with 39.6% forest and 14% smaller gardens and meadows. Agriculture composes only 1.4% and plays little role today. The wineries have mostly retreated into the hills of Schafberg.