Colombia's rapid expansion of health insurance coverage in the 1990s provides an opportunity to evaluate whether health insurance coverage positively affects health care usage and outcomes. We use the discontinuity in eligibility for the Subsidized Regime (SR), the subsidized health insurance for the poor, to see if the Subsidized Regime increased the incidence of doctor assisted births, prenatal care, and hospital deliveries; and if it improved newborn health measured by birth weight, gestation period, Apgar score and incidence of low (lbw) and very low birth weight (vlbw). We find that the Subsidized Regime had positive effects on newborn birth weight, but although positive, not consistently significant effects on other health measures or access to medical personnel and facilities.