Objective: We sought to estimate the proportion of women immunized against tetanus while attending prenatal care in the developing countries. Method: We computed the ratio of the percentage of births to women immunized against tetanus to the percentage of births to women with prenatal care (TP ratio). A TP ratio is lower than 100% if not every woman attending prenatal care is immunized. We used 1986–1992 Demographic and Health Surveys data from 38 countries. Results: The mean TP ratios were 86% in Africa (n = 23), 79% in Asia (n = 6) and 60% in Latin America and the Caribbean (n = 9). The TP ratio was lower than 75% in 15 countries. Of these, four had a TP ratio lower than 50%. Conclusion: In many countries the number of pregnant women immunized against tetanus is lower than the number of women attending prenatal care, suggesting that prenatal services are missing opportunities to immunize attending women.