AbstractSome transverse mechanical properties of composites comprising uniaxially aligned continuous glass fibres embedded in a glass microsphere‐reinforced expoxy resin matrix have been determined from three‐point bending experiments.For a constant fibre volume fraction, the transverse modulus, strength, fracture surface energy for crack initiation and work of fracture are investigated as a function of microsphere content and compared with the equivalent two‐phase composites without beads.Modification of composite transverse properties are attributed to corresponding changes in matrix properties and comparisons are made with boundary expressions established for two‐phase particulate systems. The effects of voids, microsphere size and surface treatment on the properties are also e