Most malignant melanomas of the choroid manifest themselves as easily recognized, solid, pigmented subretinal masses. Occasionally these tumors are masked by detachment of the retina and are discovered only after long delay and potentially dangerous therapy. Consequently, several techniques have been devised to differentiate malignant melanoma from other elevated lesions of the fundus, but none has been wholly satisfactory.* Diagnosis by microscopic study of aspirated subretinal fluid is one of these methods. This is an application of Papanicolaou's technique for the detection of carcinomas in other tissues, in which diagnosis is made by the appearance of individual tumor cells or clumps of cells in tissue fluids.5This method has applicability because in most malignant tumors there are a sparse stromal network and poor cellular cohesion, which permit desquamation of the surface cells. Theoretically, intraocular malignant melanomas should be ideal for such a diagnostic procedure, since the surface of