Untitled (Black on Grey) is a 1970 acrylic on canvas painting by Mark Rothko, featuring a black rectangle and a grey rectangle.

In mid-1968, Rothko suffered an aortic aneurysm and could only work on stretched paper during his recuperation. The edges were secured using gummed tape that left a white margin when removed. Later, Rothko taped the edges of his canvases before painting to produce the same effect. When asked about these paintings, he said they were about death.^{[citation needed]}