The acute endometritis is an actual medical problem in the structure of gynecological pathology and its complications result in incapacitation, infertility and lethality. The purpose of study is to ameliorate laboratory diagnostic of acute endometritis at the expense of selection of diagnostically significant and similar clusters of systemic humoral immunity. The analysis was carried out concerning parameters of systemic humoral immunity in 154 patients with post-natal acute endometritis and 103 patients with non-complicated post-natal period using the radial immunodiffusion technique. The selection of diagnostically significant parameters was implemented at the basis of indices of shifting, disintegration and cluster analysis method. The leading value for laboratory diagnostic of acute endometritis according indices of shifting, disintegration and cluster analysis among parameters of systemic humoral immunity keep content of IgA in blood, absolute number of SD20+ and circulating immune complexes. The selection of diagnostically significant and similar indices of humoral immunity permits to decrease number of detecting parameters at the diagnostic of acute endometritis. © 2017 Izdatel'stvo Meditsina. All rights reserved.