Elastic moduli of pultruded glass-fibre-reinforced polymer beam and plate profiles are presented. The method used to fabricate three beams, each with a six-plate bonded splice joint at mid-span, is outlined. Details of the instrumentation used to measure deflections, etc. during three-point flexure tests on the beams are given. Deflections, support rotations and mid-span strains recorded during the tests are presented. Formulae, based on shear deformation beam theory, are presented for predicting the centre deflection and the support rotations of the beams. It is shown that they predict deflections and rotations with a maximum error of about 10%, provided the elastic moduli are derived from coupon tests rather than the manufacturer's minimum values. The theory is extended to provide a simple method, based on the solution of a quadratic equation, for determining the optimum and limiting splice length ratios for particular values of the additional cross-sectional area and additional second moment of area factors and the shear flexibility parameter. Finally, the theory is used in three parameter studies to assess the effects of splice length ratio, adhesive thickness and modulus, splice plate thickness and splice joint layout on the normalised mid-span deflections of spliced beams.