The present study was conducted to assess the possible influx ofrnnew HIY-1 subtypes into the population of Addis Ababa, Ethiopia.rnIn an unlinked anonymous cross sectional study, 150 commercialrnsex workers (CSW) reporting in 1997 to blo STD clinics in AddisrnAbaba- Kazanchis and Tekle-Haimanot were enrolled. For HIY-1rnsubtyping, the WHO algorithm of peptide ELISA followed byrnheteroduplex mobility assay (HMA) and DNA sequencing was carriedrnout. The HIY-1 prevalence among the CSW was 44.7% (67/150).rnPeptide ELISA identified 46.3% (31/67) plasma samples to bernreactive with subtype C peptides; 30% (20/67) to be reactive withrnboth subtype C and A peptides; 3% (2/67) to be reactive withrnpeptides A, C and D; 1.5% (1/67) with peptides Band D and 1.5%rn(1/67) with peptides C and D. Six (9%) samples were indeterminatern(OD just below cut-off) and another 6 (9%) were non-reactive.rnSubtyping performed with HMA identified 86.5% (58/67) as subtypernC, 6% (4/67) as subtype A and 1.5% (1/67) as subtype D. Fourrnplasma samples remained untypable using this technique. DNArnsequencing of the gp120 Y3 regions of 8 samples (2 subtype C, 3rnsubtype A, 2 untypable and 1 aberrant sample by HMA) clusteredrnall in subtype C. One subtype D sample by HMA was found to belongrnto the same subtype by sequencing. Four samples remainedrnun typable by sequencing. In general, 95.5% (64/67) were subtypernC, 1.5% (1/67) subtype D and 3% (2/67) were untypable. Inrnconclusion, although this study provides evidence for influx of arnnon-subtype C HIY-1 strain (D) into Addis Ababa, the far majorityrnof HIY-1 infections in this city remain of subtype C.