The present study was carried out to investigate the blood markers of Thoroughbred horses (TB) The blood red cell types and blood protein types (biochemical polymorphisms) were tested from 1,125 Thoroughbred horses by serological and electrophoretic procedures, and their phenotypes, gene frequencies, heterozygosity, polymorphic information content values and exclusion probability were estimated. The blood group and biochemical polymorphism phenotypes observed with high frequency were Aaf(91.7%), Ca(94.7%), K-(94.5%), Ua(75.9%), P-(50.6%), Qabc(82.6%), ALB-BB(67.7%), GC-FF(92.7%), AIB-KK(99.6%), ES-II(77.9%), TF-DF1(23.6%), PI-LL(23.2%), HB-B2B2(73.6%), PGD-FS(45.4%) and genotypes Dcgm/dk(16.9%), Dbcm/cgm(13.6%), Dbcm/dk(11.9%), Dcegmn/cegmn(10.0%), Dcgm/cgm(8.7%) in TB. Alleles observed with high frequency were Aaf(0.796), Ca(0.769), Ddk(0.266), Dcgm(0.261), Dbcm(0.211), K-(0.972), P-(0.710), Qabc(0.565), Q-(0.368), Ua(0.509), $HB^{B2}$(0.858), $PGD^F$(0.634), $ALB^B$(0.825), $GC^F$(0.927), $AIB^K$(0.998), $ES^I$(0.881), $TF^{F1}$(0.346), $TF^D$(0.319), $TF^{F2}$(0.184), $PI^L$(0.479), $PI^N$(0.214), $PI^U$(0.116) in TB. The heterozygosity, polymorphic information content (PIC) and exclusion probability (PE) were calculated. The mean heterozygosity and PIC value were 0.3899 and 0.3375, respectively. The highest heterozygosity and PIC were estimated 0.7834 and 0.7492 in blood group D locus, respectively. The cumulated PE obtained by blood groups and biochemical polymorphisms was 0.9813.