BackgroundrnSexually transmitted infections (HIV, HBV and Syphilis) are major public health problemsrnworldwide with a highly prevalent in developing countries like Asia and Sub-Saharan Africa. Allrnof these common sexually transmitted infections share similar mode of rntransmission which isrnthese includes: receiving of blood through donation, ear piercing and history of abortion forrnHBV infection and sharing different sharp materials and contact history with infected person forrnHIV infection alone.rnConclusionrnThis study showed that HIV infection was similar with Addis Ababa HIV prevalence whereas;rnHBV infection was intermediate according to WHO classification. Syphilis was non-existing andrnHBV-HIV co-infection was very low. Therefore; not only for HIV but also for HBV infectionrnneeds to be screened for all pregnant women during pregnancy.rnKey terms: HIV, HBsAg, Syphilis, Seroprevalence, risk factors, pregnant womenrnrnhorizontal and perinatal (vertical) transmission. Their complication isnâ€™t only restricted to thernpregnant women but also to their newborn infants; rather they affects concurrently.rnObjectivernThis study has undertaken to determine sero-prevalence and risk factors of HBV, HIV andrnsyphilis infections among pregnant women attending at Gandhi Memorial Hospital, AddisrnAbaba, Ethiopia from January to April 2014.rnMethodrnA descriptive-correlational study design conducted among 403 pregnant women attending atrnGandhi Memorial Hospital, Addis Ababa, Ethiopia between January and April 2014. Participantsrnenrolled consecutively after consenting and an interview have conducted to obtain informationrnregarding risk factors. Blood have collected and screened for hepatitis B surface antigen usingrnrapid screening test strip and cassette device. After all; the final positive sample for HBsAgrnconfirmed by enzyme linked immunosorbent assay (ELISA). Moreover; Antibodies to HIV-1/2rntested based on the national testing algorism but Trepollema pallidum antibodies were byrnSyphilis Rapid Test Strip (Quick TestTM Syphilis Serum/ Plasma/Whole Blood Strip). Finally therndata entered using Epi Info version 3.5.1 and exported to SPSS version 16 so as to recode, clean,rnvalidate and analyze.rnResultsrnA total of 403 pregnant women with the mean age of 24.8 (SD+5.99) years old enrolled in thernstudy. Overall, 21/403 (5.2%) and 20 /403 (5%) of the pregnant women were positive for HIVrnand HBsAg, respectively. The co-infection of HIV-HBV was 0.5% (2/403). However; no casesrnof Syphilis detected positive. In relation to the risk factors; history of sex with multiple sexualrnpartners, pre-exposure to STI and low level of monthly income were significantly associatedrnwith both HBV and HIV, while each infection found to have additional different risk factors;