Pre-stressed hollow core slabs have been largely used in the precast concrete industry. They have also been extensively studied, especially regarding the characterisation of strength against web shear failure. However, in most of the studies reported in the literature, the pre-stressing force acting on the tested slabs was not known and torsional effects influenced the results. This work presents a simple and economical methodology that reduces the torsional effects in the tests, to evaluate the shear strength of pre-stressed hollow core slabs. From longitudinally-cut segments of 210 mm deep hollow core slabs with greased strands, the tensile strength of the concrete used in casting the hollow core slab was determined. From longitudinally-cut slab segments, the effective pre-stressing force was also determined at the time of carrying out the shear strength characterisation test. From these tests, the contribution of the concrete and pre-stressing force to the shear strength of the hollow core slab make up by slipformer machine was isolated and determined. Two failure modes were experimentally characterised from the segments, that is, flexural shear and tension shear failure. From the experimental results, an analytical model is proposed to determine the flexural shear strength of 210 mm hollow core slabs and the tension shear strength of non-pre-stressed concrete. A pre-stressed hollow core slab was also tested to validate the proposed analytical model. Additionally, the pre-stressing force transfer length in the hollow core slab was determined, obtaining a value of 65ϕ. Three databases of experimentally tested hollow core slabs, with depths ranging from 160 mm to 320 mm and a/h ratio equal to 2.5, were used to validate the proposed analytical model. A good estimate of the flexural shear strength of these slabs was obtained.