Endometriosis is defined by the presence of endometrial tissue outside the uterus. Clinical and basic research in endometriosis has been hampered severely by the lack of accurate noninvasive diagnostic techniques. Transvaginal ultrasonography, MRI, and endometrial and serum markers have the potential to facilitate the diagnosis and can be useful in the follow-up of patients. Endometriosis research has entered the postgenomic era, and powerful genomic and proteomic technology is being applied in the search for novel diagnostic and therapeutic approaches. This article explores the recent advances in imaging techniques and the development of diagnostic molecular markers of endometriosis.