Rainbow trout is a valuable species of aquaculture, which is characterized by a high level of variability. Aim. The goal was to study the peculiarities of genetic variability of rainbow trout based on polymorphism of transferrin (TF), posttransferrin (PTF), esterase (EST) (EC 3.1.1.1.) and albumin (ALB) loci. Methods. Electrophoretic separation of plasma proteins of rainbow trout from three local stocks (Chernivtsi, Kharkiv and Transcarpathian) was carried out in the native polyacrylamide gel. Results. Peculiarities of the distribution and relative electrophoretic mobility of allelic variants of the studied loci of rainbow trout of Ukrainian local stocks were established.The results demonstrated the effectiveness of the analysis using methods of biochemical genetics to establish the characteristics of the genetic structure, the level of heterozygosity of local stocks and to carry out their differentiation. Conclusion. The use of selected markers would allow monitoring the dynamics of changes in the state of local stocks under the established conditions of cultivation in the future. Key words: rainbow trout, polymorphic blood plasma proteins, transferrin, posttransferrin, esterase, albumin.