Amyotrophic lateral sclerosis (ALS) is a chronic progressive motor neuron disease with a poor prognosis which eventually weakens and paralyzes the respiratory muscles. ALS is characterized by progressive degeneration of both cortical and alpha motor neurons of the final common pathway. Early symptoms usually begin with alpha motor neuron involvement and then progress to include cortical motor neuron involvement. Degeneration of respiratory nerve centers in the anterior horn at the C3-C5 levels results in respiratory muscle fatigue, respiratory failure and eventually death. Treatment consists of preventing respiratory complications and supporting lung function for as long as possible. One case example of a critically ill patient with ALS highlights nursing concerns. With advanced directives and durable power of attorney, the patient now has better means available for making known the decision of whether to accept or reject mechanical ventilation.