227 sera from myasthenic patients were tested for the presence of anti-AChR antibodies (anti-AChR Abs) by mean of a fetal calf receptor (Fc-AChR); 73.5% of cases proved positive with this method. Significant correlations were found between presence of anti-Fc-AChr Abs and various clinical aspects such as: clinical stage and duration of disease; moreover significantly higher than the median titers were found among younger patients (i.e. age less than 40 yrs).