Design of flat slabs is usually based on separate considerutions of flexure and shear, with empirical rules similar to those used in design of beams and continuous slabs. Additionally, shear capacity of a flat slab has to account for its distinctive mode of failure known as 'punching failure' or breaking away of a portion surrounding the column from the rest of the slab. Provision against such failure is often the critical design requirement for flat slabs with or without openings adjacent to the columns. While links are normally provided to enhance the punching shear capacity, the current Codes of Practice stipulate limits on the loadcarrying capacity of flat slabs. Such limits govern the thickness of the slab and, therefore, have a direct influence on economy of construction. This paper examines the limits on loadcarrying capacity of flat slabs supported on internal and rectangular columns, which are given in BS 8110 and Eurocode EC 2, with the help of tests on slab specimens with and without openings.