A chicken β-tubulin cDNA probe has been used to screen two independently generated human genomic libraries. Of 13 EcoRI fragments detectable in a human genomic Southern blot experiment, 7 correspond in size to EcoRI fragments isolated from recombinant bacteriophage. The location of β-tubulin-specific regions and the direction of transcription were determined within each cloned fragment. One clone (5β) contained a β-tubulin-specific region of 6.8 kilobase paires (kbp) that included three intervening sequences as well as a number of inverted repeat structures. The remaining clones contained β-tubulin-specific sequences that were close to or, in two cases, substantially less than 1.9 kbp long. Because mature human β-tubulin mRNA is approximately 1.9 kbp long, these short DNA regions cannot on their own encode a functional β-tubulin mRNA. Analysis using 3' and 5'-specific probes derived from the chicken cDNA clone showed the presence of both of these end regions within one truncated tubulin-like sequence. A second short tubulin-specific region failed to hybridize with a 3'-specific probe. These short sequences are therefore likely to be examples of pseudogenes that have arisen by loss of a portion of DNA essential to the production of functional human β-tubulin mRNA.