Experiments on the buckling and ultimate capacity of thin-walled steel web plates containing circular and square cut-outs are reported. Some 64 tests were carried out on plates containing either one or two holes. The parameters varied included the size of the hole and the eccentricity of the location of the hole.For an increase in the eccentricity of the hole, the shear buckling coeficient increased when the opening was located in the compression diagonal and decreased when it was in the tension diagonal; it was found to be insensitive to the location of the hole, for small openings.Approximate formulae are suggested in the paper for computing the shear buckling coefficients for plates with central and eccentric holes, and are suitable for use by designers. A method of predicting accurately, the ultimate capacity of the web is presented.