In this study, the prevalence of HTLV 1/2 infection among pregnant women in the State of Mato Grosso do Sul was estimated by means of the ELISA, Western Blot and PCR techniques, in blood samples collected by peripheral venous puncture. 116,689 pregnant women were examined and 153 were diagnosed as presenting HTLV 1/2 infection, with prevalence of 0.13%. Among these 153 pregnant women, 133 (86.9%) had type 1 and 20 (11.1%) had type 2; 73.2% were black, brown or indigenous; about 90% performed domestic activities; and 75.8% (116/153) had been to school for seven years or less. The 153 pregnant women had 172 pregnancies during the study period and 164 pregnancies were followed. Out of pregnancies that were followed, 6.7% (11/164) evolved to abortion, 26.8% (41/153) reported previous abortions and 31.7% (13/41) had had more than two abortions. Comorbidities were found in 17% (26/153), among whom 3.3% (5/153) had HIV (p<0.000002). The authors emphasize the importance of identifying pregnant women with HTLV 1/2 infection, as a strategy for disease control and prevention.