In 12 patients with myasthenia, the content of β-adrenoreceptors on the cell surface and activity of intracellular lymphocytic enzymes were determined by EIA and biochemical methods, respectively. In comparison with the normal, these patients demonstrated pronounced elevation in the content of β-adrenoreceptors and significant changes in activity of lymphocytic enzymes. In 10 of 12 patients, administration of the agonists to β-adrenoreceptors resulted in health improvement accompanied by normalization of EMG and immunobiochemical indices. Our findings suggest that intra- and intercellular signaling pathways and their modification can serve as potential targets for the therapy.