Definitive diagnosis of HIV infection in infants < 18 months of age who were born to HIV-infected mothers is still posing some difficulty in Nigeria and other developing countries. Within this age definitive diagnosis can only be carried out by antigen based techniques which are indeed not available in these developing countries. This has resulted in the absence of authoritative data on the rate of mother-to-child transmission in these countries. Nigeria inclusive. The present pilot study was therefore carried out to generate some information on the rate of mother to child transmission in Nigeria using the PCR technique. Plasma samples were obtained from 68 children of both sexes less than 18 months of age and who were born to HIV infected mothers. The samples were collected from two pediatric departments. in Lagos and in Benin. The presence of HIV 1 RNA in each of the samples. was determined using the Amplicor Monitor V 1.5 technique (Roche Diagnostics). Data showed that HIV-1 RNA was detected in 15 of the 68 samples tested. This gave an HIV-1 RNA detection rate of 22%. Among women who had some intervention, the rate of transmission of infection was 11% while the rate among those without intervention was 30%. The 22% transmission rate recorded in this study is close to the range of 25 to 35% that has been reported in several developed and a few developing countries. A multicenter nationwide study will still be needed to determine the national mother to child transmission rate in Nigeria.