Conservation of genetic variety of strains maintained in live gene banks is a high-priority task. Description of the genetic structure should be the first step in this work. By applying different biochemical-genetic markers such as transferrin and isoenzymes, the individuals and the populations could be well characterised genetically. Based on this, breeding programs as well as conservation of races can be carried out without disappearance of genes from the pool. The aim of this survey was to describe the polymorphism of transferrins of carp strains in the live gene bank maintained at the Fish Culture Research Institute, Szarvas, Hungary. Biochemical polymorphism was studied by standard methods of horizontal electrophoresis in starch gel as well as vertical electrophoresis in polyacrylamid gel. A total of 840 breeders of 15 carp races were sampled. Identification of transferrin genotypes was made by the traditional classification. In the 15 carp populations, 20 transferrin genotypes were described (AA, BE, DD, EE, FF, GG, AB, AD, AF, AG, ED, BE, BG, DE, DF, DG, EF; EG, FG, and FH) in the presence of 7 alleles (A, B, D, E, F, H and G). The frequency of allele D was very high (0.34-0.62) in all populations except one (koi). It was remarkable that the frequency of allele D was very low (0.0698) in this group showing the highest variability, while the frequency of allele B, being very rare in all other races, was relatively high (0.27) in the group of koi.