iT WAS SHOWN that subtype B variants of human immunode- ficiency virus type 1 (HIV-1) from intravenous drug users (IDUs) differ from the variants of homosexual men in several genomic regions, including vpu , vpr , and sequences encoding the gp120 V3 loop. 1,2 The most conserved was found to be a synonymous nucleotide substitution in the second glycine codon at the tip of the gp120 V3 loop (GGC). 1 Several epi- demiological studies w ere done among the different risk groups in various European countries and the United States. GGC viruses have been found in 85% of IDUs in northern Europe and in 45% of U.S. IDUs. 3 The GGC pattern was not found in V3 sequences obtained from homosexual m en in various Eu- ropean countries and the United States.