Inclusion Criteria:

   - Age 18 years or older at registration

   - Gastric emptying scintigraphy within 2 years of registration

   - Normal upper endoscopy or upper GI series within 2 years of registration

   - Symptoms of chronic nausea or vomiting compatible with gastroparesis or other
   functional gastric disorder for at least 6 months (does not have to be contiguous)
   prior to registration with Gastroparesis Cardinal Symptom Index (GCSI) score of
   greater than or equal to 21

   - Significant nausea defined with a visual analog scale (VAS) score of greater than or
   equal to 25 mm on a 0 to 100 mm scale

Exclusion Criteria:

   - Another active disorder which could explain symptoms in the opinion of the
   investigator

   - Use of narcotics more than 3 days per week

   - Significant hepatic injury as defined by significant alanine aminotransferase (ALT)
   and aspartate aminotransferase (AST) elevations of greater than 2x the upper limit of
   normal (ULN) or a Child-Pugh score of 10 or greater

   - Contraindications to aprepitant such as hypersensitivity or allergy

   - Concurrent use of warfarin, pimozide, terfenadine, astemizole, or cisapride

   - Pregnancy or nursing

   - Any other condition, which in the opinion of the investigator would impede compliance
   or hinder the completion of the study

   - Failure to give informed consent