In April 2010, an explosion on an oil rig in the Gulf of Mexico killed 11 workers, injured 17 workers, and spilled an estimated 185 million gallons of crude oil into the Gulf. Adverse effects on the health of cleanup workers, fishermen, and others as well as on the ecosystem are being studied. This paper reviews published studies of the adverse health effects due to previous oil spills. Acute effects have included: respiratory, eye, and skin symptoms; headache; nausea; dizziness; and tiredness or fatigue. Chronic effects have included: psychological disorders, respiratory disorders, genotoxic effects, and endocrine abnormalities. We also present a systematic approach to evaluating individuals exposed to oil spills.