The human T-cell lymphotropic virus type 1 (HTLV-1) was the first human retrovirus known as a direct causal agent of a malignant disease. The vertical route of HTLV transmission is the most frequent pathway of the virus contamination. This study was performed to determine the prevalence ratio of HTLV-1 infection among nursing women. From January 2004 to January 2005, blood samples from 1033 nursing mothers from Paraíba, Brazil were evaluated for HTLV antibodies by ELISA and HTLV-1 viral particles confirmed by polymerase chain reaction (PCR). HTLV antibodies were detected in 7 women. The overall seroprevalence ratio was 0.68% and HTLV-1 viral sequences were confirmed by PCR in 2 women. These preliminary data suggest that HTLV screening should be introduced as a mandatory test before breastfeeding and breast milk donation in Paraíba, Brazil. Additionally, counseling programs would help reduce the prevalence ratio of HTLV-1 infected individuals in this Brazilian region. J Hum Lact. 24(3):289-292.