Simple radial immunodiffusion method was applied to the study of serum immunoglobulin A, M, and G content in healthy persons (donors), depending on age, sex and blood group reference by the ABO system. Mean serum immunoglobulin level in (IU/ml) in healthy persons was found to be as follows: A--123.8 +/- 3.4, M--143.3 +/- 3.8, and G--139.9 +/- 2.8. There were revealed higher indices of immunoglobulins of class G, and particularly of M in women; no statistically significant differences were found in the serum immunoglobulins content depending on age and blood reference, at the same time their connection with sex (in women) was detected.