Amyotrophic lateral sclerosis (ALS) is the most common adult motor neuron disease (MND), presenting with a combination of upper (UMN) and lower (lmn) motor neuron signs, with high mortality. other less frequent mnd are progressive muscular atrophy (pma) and primary lateral sclerosis (pls).To describe demographic data, clinical forms of presentation and evolution of patients with MND, looking for prognostic indicators factors.Retrospective study of a series of patients with MND, registering demographic data, clinical variables and mortality-survival, analyzed by means of statistical package SPSS 6.1.2.They are 54 patients with MND (50 ALS, 3 PMA and 1 PLS), 30 (55.6%) men and 24 (44.4%) women, bulbar beginning forms in 13 cases (24.1%) and spinal in 41 (75.9%). Average age at beginning 60+/-14 (29-82 years), more delayed in women (p<0.05), and in patients with bulbar form (p<0.05) with clear predominance of female sex (p<0.03). There are 31 dead patients (57.4%) and 23 alive ones (42.6%), with average survival from the beginning symptoms of 46.51+/-40.9 months. Nine months (11-209), observing inversely proportional relation with the age of beginning of the disease (p<0.02). Bulbar beginning forms (p<0.01) and LMN affectation signs, specially bulbar and cervical levels (p<0,005), are associated with a greater probability of dying while the existence of UMN affectation signs on imaging techniques 362 ques has a greater probability of survival (p<0,05).The advanced age and the bulbar beginning forms are factors of bad prognosis, specially the predominant affectation of LMN over UMN.