Two plaque-pure phage lambda clones designated as λhtX-l and λhtX-2 that hybridized to unfractionated bovine liver tRNA were isolated from a human X chromosome-specific library. The λDNAs were characterized by restriction mapping and Southern blot hybridization techniques. The human DNA segment in λhtX-l contains five or more presumptive tRNA genes and at least one Alu family member. The 19-kilobase human DNA insert in λhtX-2 contains two or more presumptive tRNA genes and at least three Alu family members. Another human genomic clone designated λhVKV7 hybridized to mammalian valine tRNA IAC. The clone was characterized by physical mapping and Southern blot hybridization techniques. The 18.5-kilobase human DNA fragment in λhVKV7 contains a cluster of three tRNA genes and at least nine Alu family members.