Anti-acetylcholine receptor antibodies(AAR)are considered pathognomonic and pathogenetic for myasthenia gravis(MG). AAR detection confirms clinical diagnosis of MG However, AAR is rarely detected in patients without MG The underlying pathophysiological mechanisms in a normal subject without MG have not been adequately addressed in previous studies. The present study reports on a case study of a healthy, elderly man with high AAR titers for 14 years. Pathophysiological mechanisms could be due to AAR heterogeneity in specificity, affinity, and multiform, and to muscle variability in response to AAR.