This chapter will review non-invasive tests which have been studied in the past, and the current diagnostic tests available for endometriosis. It will also deal with some of the current attempts by researchers in the field to develop new less invasive tests for endometriosis. Endometriosis is a common and often debilitating gynecological condition. The usually long delay in diagnosis is partially attributable to the fact that the only reliable diagnostic test at present involves an invasive and costly surgical procedure. While laparoscopy seems likely to maintain a central role in the treatment of the disease at present, via excision or ablation of endometriotic lesions, the development of non-invasive and less costly screening tests should be a priority in advancing the treatment of the disease. Most of the currently available non-invasive diagnostic methods, including monitoring of symptoms, serum tests, and imaging techniques, have major flaws in diagnosing endometriosis. While several new lines of investigation are emerging with the application of genomic and proteomic profiling of eutopic endometrium, more work is urgently needed in this area.