SummaryThe bovine major histocompatibility complex differs from that of other species in that it has a second group of class II genes that are separated from the classical class I/class II complex by 15 to 20 centimorgans. Two class II bovine genes,BoLA‐DYAandBoLA‐DIB, seem to be unique based on sequence analysis. To investigate the occurrence of one of these genes,BoLA‐DIB, in other species, aDIB2nd domain exon probe was hybridized to Southern genomic blots containing DNA from representatives from a variety of mammalian families. The probe hybridized only with DNA from representatives of the Cervidae, Giraffidae and Bovidae families, indicating that significant sequence similarity toDIBmay be confined to these families. Analysis of the linkage relationship betweenDIBandDOBin cattle half‐sib families did not yield any recombinants among 39 informative offspring, indicating thatDIBmaps within the second group of class II bovine genes;DOBhas previously been mapped to the second group of class II genes. A 1st domain exon probe fromBoLA‐DQBhybridized to RNA from either stimulated or unstimulated peripheral bovine lymphocytes, while 1st domain exon probes fromBoLA‐DIBandHLA‐DOBgave no hybridization signals, indicating that transcription in peripheral lymphocytes of these genes is at least very minor compar