In a 12-month period 26 eyes were enucleated after an ultrasonographic diagnosis was made of malignant melanoma of the choroid. Histologic features of the tumors were reviewed. The ultrasonographic diagnosis was correct in 100% (26/26) of enucleated eyes. Spontaneous vascular movement (SVM) was identified by standardized A-scan echography in 69% (18/26) of the tumors. Contact B-scan ultrasonography demonstrated choroidal excavation in 65% (17/26) of the melanomas. During the 12-month study period, choroidal excavation was also demonstrated in cases of metastatic choroidal tumors, hemangiomas of the choroid, and long-standing choroidal nevi. The standardized A-scan finding of SVM is a compelling sign in the diagnosis of choroidal malignant melanoma. In contrast, the B-scan finding of choroidal excavation is a less useful sign since it may also be seen in various other ocular lesions.