The lady’s boudoir can be reached from the corridor or directly from the living room via a private stair belonging to the lady of the house. Most unusually, the room is divided horizontally into two levels, linked by a short flight of steps.
In the upper part of the boudoir are a glazed case, built-in bookshelves and a recess with an inset couch and a round, Oriental table with a loose brass top. The original French, quilted cretonne cover with a floral pattern has survived on the couch. Above the couch is a window looking out over the living room, which can be opened - as on a train - by sliding it down into the wall. The window facing outdoors has a surprisingly high sill - according to Loos, it was not necessary for the lady of the house to see what was going on in the street. The relaxing corner is complemented by a standard lamp with a parchment shade.
Several steps lead down into the lower part of the boudoir, the two sections of the room being divided by an open bookcase. The settee with loose flat and rolled cushions has a cover similar to that above, and again, it is the original material. The boudoir further contains an egg-shaped rattan chair with floral upholstery, which unlike its counterpart in the living room has no arms. At one point a jewellery box stood beneath the window, but this has not survived.
The furniture and panelling of the lady's boudoir are made using rare lemonwood veneers with a warm, golden colour. They were made to Adolf Loos' design by the Prague firm of Emil Gerstel. The whole floor of the boudoir is covered by a green felt, covered in the lower area by an Oriental carpet.
Five prints with erotic themes hang in the lady's boudoir, and again these pictures are from Dr. Müller's collection. Two of these, Pierre Antoine Baudoin's "L´epouse indiscréte" and Watteau's "Italienische Serenade" were hung by Loos in the entrance to the room, above a low bookcase; the other three were places in the lower part of the boudoir, over the settee. The first two of the latter could be identified from photographic documentation as La baiser à la dérobée and Le verrou (both by Honoré Fragonard), while the third, which was probably Balancoire (again by Fragonard) cannot be reliably confirmed.
Loos installed an interesting light fitting, made from a rock crystal block, on the low parapet of the steps joining the upper and lower parts of the boudoir. Traditionally it is said to have been made to his design.