18 patients with typical sporadic Amyotrophic Lateral Sclerosis (ALS) were investigated by the Motor Accuracy and Speed Test (MAST) and 18 healthy age- and-sex-matched volunteers, acted as controls. All performed each of the five tests 10 times with both the right and the left hands and repeated the experiment after one week by the same procedure. Motor performances were better in the controls than in the ALS patients only in the first three tasks. At retest, one week later, the controls generally improved while ALS patients did not. The mean percentages of changes showed a statistically significant difference in the fifth task. Analysis of the results suggests the possibility that, among the other mechanisms, a disturbance of motor learning ability could be operating in ALS patients.