The Orphan Drug Act was enacted in 1983 to stimulate drug development for rare diseases. How well this law has accomplished that goal is an important public health question. This study examined the characteristics of the 209 orphan drugs approved as new molecular entities in the period 1983–2014. As a whole, these drugs were highly innovative and provided substantial gains in reducing unmet medical needs for rare diseases: Over 50 percent of the drugs were first in class, and 78 percent received a priority review. Drugs approved as either therapeutic or supportive therapies for rare cancers represented the highest proportion of these drugs (35 percent). Additionally, in 2010–14 large companies became a strong presence in developing orphan new molecular entities for oncology indications. Overall, new orphan drugs appeared to be highly innovative and provided important advances in care for patients with rare diseases.