Little is known about how marine protected areas (MPAs) may be vulnerable to vessel oil spills in the United States. This study investigated individual size, frequency, and total amount of vessel oil spilled in US MPAs, and how characteristics of MPAs and individual spill events influenced spills. Vessel oil spills in US waters (2002-06) and MPA boundaries were mapped. Total number and volume of oil spills inside and outside MPAs were computed. Results show that the presence of a MPA does not seem to prevent vessel oil spills or reduce the amount of oil spilled, and that a variety of MPA attributes (e.g., scale of protection, fishing restrictions, and others) and spill event characteristics (e.g., vessel type, year of spill, and others) affect oil spills inside and outside MPAs. These results can be used to develop MPA rules and marine transportation policies that reduce the vulnerability of sensitive resources to oil spills.