Grisaille ( or ; French: grisaille, lit. 'greyed' French pronunciation: ​[ɡʁizaj], from gris 'grey') is a painting executed entirely in shades of grey or of another neutral greyish colour. It is particularly used in large decorative schemes in imitation of sculpture. Many grisailles include a slightly wider colour range.

A grisaille may be executed for its own sake, as an underpainting for an oil painting (in preparation for glazing layers of colour over it) or as a model from which an engraver may work (as was done by Rubens and his school). Full colouring of a subject makes many demands of an artist, and working in grisaille was often chosen as it may be quicker and cheaper than traditional painting, although the effect was sometimes deliberately chosen for aesthetic reasons. Grisaille paintings resemble the drawings, normally in monochrome, that artists from the Renaissance on were trained to produce; as with drawings, grisaille can betray the hand of a less-talented assistant more easily than would a fully coloured painting.