Conserved regions of the gag, pol, and env genes of HIV-1 pBH10 DNA (gag nucleotides(nt)1508-1652, pol nt 2811-3118, env nt 7792-7934; Ratner et al., 1985) were amplified by the polymerase chain reaction (PCR) using oligonucleotides complementary to the termini of these regions as primers. Primer areas of the amplified DNA were then removed by digestion with restriction endonucleases, and the internal fragments purified and cloned in both orientations into the riboprobe transcription vector pGEM-5Z. Riboprobes made from these plasmids did detect the specific sequences of pBH10 DNA and of HIV-1 DNA amplified by PCR from clinical material. The riboprobes will be useful to confirm the specificity of PCR-amplified fragments of lymphocyte DNA obtained from infants of HIV-infected mothers and from high risk, but seronegative contacts of HIV-1 infected individuals.