Methods. A longitudinal observational study in a consecutive sample of patients diagnosed with ALS will be realized. All the patients will be examined 3 times during 6 months and capabilities associated with ALS and muscle strength will be assessed. Bilateral and cross sectional ultrasonography of several muscles and also median and tibial nerves will be performed. All the images will be processed and analyzed for obtaining morphometric variables (muscle thickness and nerve area) and textural ones (echogenic variation, entropy, homogeneity, textural contrast and correlation). Frequency of twitches will be also recorded. After longitudinal study, a survival study will be performed in relation to functional and sonographic variables.