Currently, there is no adequate technology to detect early stage ovarian cancers. Most of the cancers in the ovary are detected when the cancer has already metastasized to other parts of the body. As a result, ovarian cancer has the highest mortality of all gynecologic cancers with a 5-year survival rate of 30% or less. Thus, there is an urgent need to improve the current diagnostic techniques. Photoacoustic imaging (PAI) is an emerging modality with a great potential to assist ultrasound for detecting ovarian cancer noninvasively. In this article, we report the first study of coregistered ultrasound and PAI of 33 ex vivo human ovaries. An assessment of the photoacoustic images has revealed light absorption distribution in the ovary, which is directly related to the vasculature distribution and amount. Quantification of the light absorption levels in the ovary has indicated that, in the postmenopausal group, malignant ovaries showed significantly higher light absorption than normal ones (P = .0237). For these two groups, we have obtained a sensitivity of 83% and a specificity of 83%. This result suggests that PAI is a promising modality for improving ultrasound diagnosis of ovarian cancer.