Unsafe abortion is a significant cause of death and ill health in women in the developing world. A substantial body of research on these consequences exists, although studies are of variable quality. However, unsafe abortion has a number of other significant consequences that are much less widely recognized. These include the economic consequences, the immediate costs of providing medical care for abortion-related complications, the costs of medical care for longer-term health consequences, lost productivity to the country, the impact on families and the community, and the social consequences that affect women and families. This article will review the scientific evidence on the consequences of unsafe abortion, highlight gaps in the evidence base, suggest areas where future research efforts are needed, and speculate on the future situation regarding consequences and evidence over the next 5–10 years. The information provided is useful and timely given the current heightened interest in the issue of unsafe abortion, growing from the recent focus of national and international agencies on reducing maternal mortality by 75% by 2015 (as one of the Millennium Development Goals established in 2000).