Amyotrophic lateral sclerosis (ALS) is a fatal neuromuscular disease, characterized by progressive degeneration of upper and lower motor neurons in the cortex and spinal cord. Although the pathogenesis of ALS remains unclear, evidence on the role of the clonotypic immune system is growing. Adaptive immunity cells often appear changed in number or activation profile peripherally and centrally. However, their role in ALS appears conflicting. Data, from human and animal model studies, currently reported in literature show that each subset of lymphocytes and their mediators may mediate a protective or toxic mechanism in ALS, affecting both its progression and risk of death. In the present review article and attempt is made to shed light on the actual role of the cellular clonotypic immunity in ALS by integrating recent clinical studies and experimental observations.