Health concerns related to the quality of the environment in offices, schools, homes, and residences have increased dramatically over the past 2 decades. One health problem frequently confronting medical practitioners and often attributed to environmental quality problems is idiopathic environmental intolerances (IEI). Formerly known as multiple chemical sensitivities, IEI is an acquired disorder characterized by adverse reactions attributed to exposure to a variety of substances under ordinary conditions. Alleged precipitants include solvents, pesticides, detergents, dusts, and fragrances. Symptoms include fatigue, malaise, headache, concentration and memory difficulties, lightheadedness, cough, hoarseness, and rhinitis without objective physical signs or consistent laboratory abnormalities. The role of the environment in precipitating these complaints continues to be controversial, and no intervention or treatment has thus far been proven to be effective. While not progressive or life threatening, IEI is often functionally disabling and very distressing to affected individuals. The investigation of IEI should involve, at a minimum, a clinical evaluation of the affected person and in most cases an environmental evaluation as well. IEI should be managed without overutilization of diagnostic tests or prescription of unnecessary environmental, occupational, or dietary restrictions.