Hybrid composites, based on unidirectional fibres of carbon and glass, in an epoxy matrix have been used to investigate the possibility of a hybrid effect. The hybrid effect is observed experimentally by values for both composite strength and composite failure strain, which are increased compared to a simple model. The introduction of an increase of the failure strain of the carbon fibre part (the “fibre”) of the composite, described by a factor H for the increase of the failure strain, results in theoretical curves for strength and failure strain, which are in general agreement with the experimental data. For the present hybrid composites a value of 푯 = ퟏ.ퟐퟐ is required, meaning a positive hybrid effect on “fibre” strain of 22%. It is thus concluded that the simple concept of a hybrid factor H for the fibre failure strain can describe the observed hybrid effect satisfactorily.