Several tests have been developed to diagnose HIV/AIDS and detect the presence of anti-HIV-1rnantibodies. But, these tests were not able to distinguish recent from established infections whichrnare particularly useful in estimating the incidence of HIV-1. Recently, a simple enzymernimmunoassay was developed that detects increasing levels of anti-HIV IgG after seroconversionrnand can be used for detecting recent HIV-1 infections to estimate incidence. This involves use ofrnthe branched peptide that includes gp41 immunodominant sequences from HIV-1 subtypes B, Ernand D allowing detection of HIV specific antibodies among various subtypes including the HIV-1rnsubtype C, which is accountable for the intense epidemic observed in Ethiopia. Therefore, thernobjective of this study was to use this assay to detect recent infections and estimate HIV-1rnincidence rates among five regions (Addis Ababa, Tigray, SNNPR, Oromia, and Amhara),rnspecific areas (urban and rural) of these regions and make comparison of HIV-1 incidence ratesrnamong different age groups in the selected regions by using cross sectional samples collectedrnfrom pregnant women who attended Antenatal Care Clinics in the 2005 HIV surveillance inrnEthiopia. However, some specimens from persons with longer-term infection could be classifiedrnas recent by the assay and this can inflate the incidence estimate. Thus, the incidence estimaternwas adjusted for misclassifications by using a recently developed formula. The adjustment forrnmisclassification is a dynamic formula correcting for the imputed sensitivity and specificity of thernassay based on the analysis of specimens with known dates of seroconversion and maintained thernincidence estimate closer to the observed incidence. As a result, the study showed a nationalrnadjusted incidence rate of 2.05% (95% CI, 1.83-2.26) in pregnant women aged 15-49 (urbanrn3.13% (95% CI, 2.71-3.55) and rural 1.24% (95% CI,1.00-1.46)). The highest proportion ofrnrecent infections (P 0.05). Incidence of HIV-1 was found to bernhigher in the urban areas except for Amhara where the reverse was true. Age wise the highestrnproportion of recent infections was detected in the age group between 15-19 years (32.2%)rn(P