Two cases (siblings) with computed tomography showing slow attenuation of basal ganglia are reported. In case 1 the abnormality is larger, bilateral and the most important neurological features are: dystonic postures mainly in lower extremities and very active patellar reflexes with sustained knee clonus on both sides. In case 2 the tomographic examination disclosed a similar, but more discrete lesion only on the left side; the neurological examination is normal despite a history of frequent falls. The authors discuss the differential diagnosis from a clinical and tomographic approach.