A complete ocular examination is essential for the correct diagnosis of a malignant melanoma of the choroid. The single, most important technique is indirect ophthalmoscopy associated with biomicroscopy of the fundus. Fluorescein angiography may provide additional arguments for malignancy, but with this method it is not always possible to differentiate a malignant melanoma from a suspected naevus or even a choroidal metastasis. Fluorescein angiography provides however a detailed and objective document which allows a better follow-up of suspected lesions. As with infrared angiography, choroidal vessels are more readily seen, this technique may prove to be of diagnostic importance. A- and B-scan ultrasonography are essential to precisely measure a choroidal lesion. Especially A-scan may also allow tissue differentiation. Diaphanoscopy is especially useful in the diagnosis of choroidal haemangioma. Even naevi may provide relative or absolute scotomas. The diagnostic importance of perimetry is therefore very limited. CT-scan and especially MRI are helpful in detecting extra-ocular extension. In case of atypical naevi, a close observation for potential growth is advised. Malignant melanomas of the choroid have to be differentiated from other fundus tumours, but also from inflammatory and degenerative conditions.