Noninvasive ventilatory assistance, in ALS patients, with the bilevel intermittent positive air pressure (Bipap) was studied, in a prospective and controlled trial, by the authors. Twenty ALS bulbar patients, fulfilling El Escorial criteria for probable or definite disease, were selected. For the follow-up all patients were submitted to evaluation with the Norris scale, modified Barthel score and an analog scale of life satisfaction, every 3 months. All patients were also submitted to respiratory functional testing (RFT). Ten of these patients were treated with palliative management (group I), the remaining ten patients received Bipap support (group II). Clinical evolution curves and clinical parameters were not statistically different in both groups, except for the percentage of actual predicted value of vital capacity (p < 0.03), showing a more advanced disease in group II patients. Analog scale of life satisfaction showed improvement in the group II, even after the beginning of respiratory insufficiency, though without significance probably due to the small sample size (p < 0.1). Since 6 patients in group II are still alive survival rates were compared with log rank test considering cumulative survivals with Kaplan-Meier estimates. Total survival and survival from diurnal abnormalities in gas exchange (survival 1) were significantly longer for group II (p < 0.006 and p < 0.0004, respectively). In spite of the small number of patients, preliminary results strongly support the importance of BIPAP in ALS patients, though further studies must go on in order to optimize the best time for introducing Bipap.