Xeroradiography is a useful screening-method for the evaluation of soft tissue alterations in the region of the poplitea. It proves that recognition of Baker's cysts, aneurysms, and even tumours is possible due to morphological criteria which allow for differentiation to a degree. The conformation of a lesion by means of arthrography or angiography is not to be dispensed with, but xeroradiography permits the objective demonstration of a clinically uncertain alteration. This method has demonstrated its usefulness especially for the rheumatologist in the evaluation of Baker's cysts.