The present invention provides devices and methods for attachment of an endolumenal gastrointestinal device, such as an artificial stoma device, a gastrointestinal bypass sleeve or other therapeutic or diagnostic device, within a patient's digestive tract. In one application of the invention, an endolumenal bypass sleeve is removeably attached in the vicinity of the gastroesophageal junction to treat obesity and/or its comorbidities, such as diabetes. The bypass sleeve may be at least partially deployed by eversion.