A unidirectional reinforcement and a method of producing a unidirectional reinforcement for use in applications where high quality and strength is required. The unidirectional reinforcement includes transversely arranged thin discrete flow passage formed to ensure resin flow properties in a direction transverse to the direction of the unidirectional rovings. Thin discrete flow passage forming means are secured on the unidirectional rovings by means of additional yarns running on the thin discrete flow passage forming means and transverse thereto.