The visual diagnosis of endometrioma at laparotomy in 245 women operated on for ovarian cysts demonstrated a sensitivity of 97%, specificity of 95%, positive and negative predictive value of 98% and 94%, respectively, and overall accuracy of 96%. Because the visual detection of endometriomas is remarkably accurate, ovarian biopsy, although desirable in some cases, would seem dispensable for a correct laparoscopic diagnosis and staging of the disease.