Two rabbit germ-line VH gene segments have been isolated from a recombinant phage DNA library. Nucleotide sequence analysis indicates that both of the genes share structural and regulatory features common to mouse and human VH genes, although one appears to be a pseudogene. Comparison of the protein sequences encoded by these genes to the protein sequences of rabbit immunoglobulin V regions indicates that both genes encode VH a-negative-like molecules. Quantitative genomic blot analysis with a VH probe capable of recognizing most, if not all, germ-line VH genes indicates that there are approximately 100 VH genes in the haploid genome of rabbits. The average spacing between the germ-line VH genes was determined to be approximately 6 kb. The molecular basis for the allelic inheritance of rabbit VH allotypes is discussed in view of the structural organization of germ-line VH genes.