A new Hessian fly (Mayetiola destructor Say) resistance gene from Aegilops triuncialis and its transfer to hexaploid wheat via interspecific hybridisation is described. The transfer line TR-3531 (42 chromosomes), derived from the cross [(Triticum turgidum x Ae. triuncialis) x Triticum aestivum] and carrying the Heterodera avenae resistance gene Cre7, showed a high level of resistance to the M. destructor biotype prevailing in the SW of Spain. A single dominant gene (H30) seems to determine the Hessian fly resistance in this introgression line, and its linkage with an isozyme marker (Acph-U1) has also been studied. It has been demonstrated that the resistance gene H30 in the TR-3531 line is non-allelic with respect to the genes H3, H6, H9, H11, H12, H13, H18 and H21, present in wheat cultivars from the Uniform Hessian Fly Nursery (UHFN), as well as to H27, carried by the introgression line H-93-33. Advanced lines with the H30 gene were obtained by backcrossing the transfer line and different commercial wheats as recurrent parents. Several of them showed a high yield in tests carried out in the infested field. Electronic Supplementary Material is available if you access this article at http://dx.doi.org/10.1007/s00122-002-1182-z. On that page (frame on the left side), a link takes you directly to the supplementary material.