Kasten-brust armour (German: Kastenbrust — "box-shaped breast") — is a German form of plate armour from the first half of 15th century.

Kasten-brust armour was a style of early gothic armour widely used in the Holy Roman Empire. Typical harness construction consists of: a grand-bascinet helm or a bicoque helmet, box-shaped cuirass, gauntlets with a long cuff and a rectangular cutout and a plate skirt known as a tonlet. Only four verified breastplates are known to have survived until today and are housed in Kelvingrove Museum in Glasgow, the MET in New York, German Historical Museum in Berlin,^[1] and Rathaus Museum of Vienna.

Kasten-brust armour is widely represented by paintings and statues of the first half of the 15th century. A style featuring a sharp ridge at the apex of the breastplate first shows up in art during the first decade of the 15th century. By 1420 a more rounded shape begins to appear in art, sometimes with fluted embellishments. This style did not necessarily supplant the earlier style- both variety appear alongside each other in the lower left panel of the Ghent Altarpiece, which was completed in 1432. The style apparently fell out of widespread use in most of Europe by 1450, however frescoes found in Gierslev Sogn indicate the style remained in use in Denmark into the last quarter of the 15th century.