The painting is of a young woman seated with one leg tucked underneath the other. Thea Brachmann is the women pictured, a student who was believed to be a girlfriend of Chagall at the time. Brachmann was both confident and well educated, and these personality traits have been captured in the painting with the sitter staring straight at the viewer without apology. The limbs are strong and the positioning of the bent leg is very reminiscent of the nudes of Henri Matisse. Chagall was introduced to works of Matisse during his time in St Petersburg.
Chagall is known for his use of strong colour. Using mainly the colour red in this painting, it's what sets the work apart from earlier pieces by the artist. Chagall uses colour like no other artist and understands how different shades of the same hue can be used in place of a full palette of colours. Red is, of course, the colour of Russia, and also of passion, sensuality and danger and he is well aware of the symbolism. The artist has used confident black lines to ensure the sitter's figure stands out, especially around the curve of the waist and the nape of the neck. Highlights of a pale rose tone draw the eye to the breast, stomach, knee and inner thigh further enforcing the highly sensualised atmosphere of the painting.
The Red Nude Sitting Up figure completely fills the canvas. There is nothing shy or awkward about the sitter, in fact, she seems unashamedly comfortable in her nudity. The background has no importance and there is nothing to show where this is. Interestingly, there is a small plant to the right of the painting. The colour green is used - the opposite tone to the red used for the rest of the image. Perhaps it is to show that the artist is not completely consumed by the subject, distraction is possible.
In the same year that Red Nude Sitting Up was painted, Chagall met his future wife, Bella Rosenfeld. In complete contrast, a painting of Bella entitled My Fiancé in Black Gloves uses more gentle lines and there is no red colour on this canvas at all. When regarded side by side, it is clear one image is filled with lust and the other with respect and awe.