Objective. An aim of the study was to compare informative value of traditional approach (anti-AChR antibody radioimmunoassay) and evaluation of metabolic shifts by laser correlation spectroscopy in myasthenia gravis. Material and methods. The search for the relationship between the disease severity in 77 patients, 12—80 years and the distribution pattern of subfraction serum components revealed three informative zones: 6—15, 27—67, and 127—223 nm. Results and conclusion. In patients without disturbances of vital functions, the contribution of the first zone particles into light scatter increases and that of the third zone particles decreases. Considerable differences attaining the level of statistical significance in zones 6 and 20 nm were revealed in the spectra of serum from patients with myasthenia gravis of the same severity with and without thymoma. This opens prospects for dynamic monitoring of the efficiency of therapy.