Box-girder analysis and design should take into consideration stresses due to longitudinal bending moment, shear force, torsion, distortion, shear-lag and transverse bending as well as instability of the flange under compression and web under shear as plates and stiffened panels. The orthotropic nature of FRP has to be taken into consideration in all these analyses. Although general purpose finite element software can be used to accurately analyse such a bridge considering all these effects, the time consumed is too high to practically use it in the preliminary and optimum design stages, which involve a large number of trials. A simplified and computationally efficient procedure for the analysis of single cell FRP box-girder bridges made of blade angle or T stiffened panels, for efficient use at these stages, is presented in this paper. This has been validated by comparison with results available in literature or results obtained from finite element analysis. © 2003 Elsevier Science Ltd. All rights reserved.