The coinfection of HIV and hepatitis B virus (HBV) and their vertical transmission constitute a public health problem in sub-Saharan countries of Africa. The objectives of this research are: i) identify the pregnant women that are coinfected by HIV and HBV at Saint Camille Medical Centre; ii) use three antiretroviral drugs (zidovudine, nevirapine and lamivudine) to interrupt the vertical transmission of HIV and HBV from infected mothers; and iii) use the PCR technique to diagnose children who are vertically infected by these viruses in order to offer them an early medical assistance. At Saint Camille Medical Centre, 115 pregnant women, aged from 19 to 41 years, were diagnosed as HIV-positive and, among them, 14 coinfected with HBV. They had at least 32 weeks of amenorrhoea and all of them received the HAART, which contained lamivudine. Two to six months after childbirth, the babies underwent PCR diagnosis for HIV and HBV. The results revealed that, among these mothers, 64.4% were housewives, 36.5% were illiterates, and only 1.7% had a university degree. The rate of vertical transmission of HIV and HBV was 0.0% (0/115) and 21.4% (3/14), respectively. The 3 mothers who transmitted the HBV to their children had all HBsAg, HbeAg, and HBV DNA positive. An antiretroviral therapy that in addition to zidovudine and nevirapine includes lamivudine could, as in the present study, block or reduce the vertical transmission in HIV positive pregnant women who are coinfected with HBV.