Background: The priority of the Gambia government is to eliminate maternal to child transmission of HIV and in line with this priority, the country implemented an antiretroviral therapy (ART) program. With this, all HIV infected pregnant and breastfeeding mothers and infants have access to ARV drugs. This study aims to determine the prevalence of vertical transmission of HIV among women receiving the ARV drugs. Methods: Dried blood spot samples were collected from 109 HIV-exposed infants enrolled in 13 PMTCT sites across the country. A qualitative detection of proviral-DNA of HIV-1 was performed using the Real Time Abbott PCR assay. Data from 105 mothers were analyzed using SPSS version 16.0 and association of risk factors to PCR results were analyzed using (Crosstabs) Pearson Chi-Square. The p-value of significant was set at p<0.05. Results: This study has found the prevalence of vertical transmission of HIV is 0.0% (0/64) among women that received the ARV prophylaxis then started ART, 7.1% (2/28) among mothers that received HIV prophylaxis only, and 38.4% (5/13) among women who neither receive HIV-prophylaxis nor ART during pregnancy or breastfeeding. Other risk factors of vertical transmission such as late initiation of treatment, default during treatment and first born of twins were found to be significantly associated with vertical transmission p=0.001, p=0.022 and p=0.000 respectively. Conclusion: This study has found that the early intervention of ART at the onset of pregnancy through breastfeeding can eliminates Maternal to Child transmission of HIV and a high risk of vertical transmission was found among women who neither receive prophylaxis nor ART. If the effectiveness of the antiretroviral therapy is maintain, the Gambia, in the near future will attain the WHO’s goal to eliminate Maternal to Child transmission of HIV.