Stable wheat-Aegilops introgression lines with 42 chromosomes (H-93), derived by repeated selfing from a cross (Triticum turgidum x Aegilops ventricosa) x T. aestivum, have been characterized using the following DNA probes and isozyme markers: (1) single or low-copy DNA fragments from Ae. ventricosa; (2) known cDNA probes corresponding to α1-thionin, monomeric α-amylase inhibitor, the CM3 subunit of tetrameric α-amylase inhibitor, and sucrose synthase from wheat; (3) anonymous cDNA probes from wheat that have been mapped by Sharp et al. (1989); (4) isozyme markers corresponding to aconitase, shikimate dehydrogenase, adenylate kinase, and endopeptidase. Meiotic metaphases of appropriate hybrids involving selected H-93 lines have been investigated by the Giemsa C-banding technique. The substitution of whole chromosomes [(5A) 5M(v); (4D) 4M(v); (5D) 5M(v); (7D) 7M(v)] and chromosomal segments (1M(v); 3M(v); 5M(v); 7M(v)) from the M(v) genome of Aegilops ventricosa has been demonstrated. The distribution of selected markers among putative wheat-Ae. ventricosa addition lines has also been investigated. The 7M(v) addition has been characterized for the first time, while the identity of the previously reported 5M(v) and 6M(v) additions has been confirmed.