Noninvasive diagnosis of solid benign and malignant tumors presents a unique challenge to all imaging modalidies. Ultrasound is routinely used in conjunction with mammography to deffierenciate simple cysts from solid lesions. However, the overlapping appearances of benign and malignant lesions make ultrasound less useful in differenciating solid lesions, which results in a large number of normal biopsies. Optical tomography using near infrared diffused light has a great potentional for imaging functional parameters of tumor total hemoglogin concentration, oxygeon saturation, and metabolism, etc, and these parameters can differenciate benign from malignant lesions. However, optical tomography alone suffers from low spatial resolution and target localization uncertainty due to the intensive light scattering inside the tissue. Our aims were to combine diffused light imaging with conventional ultrasound for detection and diagnosis of solid lesions. Initial findings of palpable and non-palpable solid breast lesions have shown that early stage invasive cancers have much higher total hemoglobin concentration due to angiogenesis than benign lesions. Furthermore, the spatial distribution of the total hemoglobin concentration is well localized in small invasive cancer cases, and is quite diffused in benign lesions.