A catalyst housing (1) which is part of a vehicle exhaust system, said catalyst housing (1) including an elliptical intermediate part (2) which encloses a monolithic catalyst body (4). An inlet part (7) connects the intermediate part (2) with a cylindrical inlet pipe (8), through which exhaust gases are intended to flow into the catalyst housing (1). With the object of simplifying the configuration of the inlet part (7), which has a supporting function in the catalyst housing (1), the pipe (8) is provided with an end portion (9) thrusting into the inlet part (7) and formed with two diametrically opposed impressions (10). These impressions converge towards each other towards the inner end (11) of the end portion (9) such that a symmetrical constriction of the end portion (9) is obtained. Two branch ducts (12) formed by the constriction enable distribution of the gas flow over the entire elliptical end wall surface (15) of the catalyst body (4).