AbstractIsozymes are useful biochemical markers in plant breeding. This paper presents the first results on the inheritance of three enzyme systems: diaphorase (DIA), glutamate oxalacetate transaminase (GOT) and phosphoglucoisomerase (PGI) from leaves ofDaucus carotaL. ssp.sativusand the linkage relationships among these isozyme loci, markedDia,Got, andPgi. Methods of extraction and electrophoresis are described. Segregation ratios indicated that the DIA system is controlled by three genes:Dia‐1, Dia‐2 and Dia‐3, Dia‐1as invariant. Two codominant alleles and a null allele were found forDia‐2, and four codominant alleles forDia‐3‐GOT isozymes are encoded by three genes;Got‐1, Got‐2 and Got‐3. An active allele and a null allele were observed forGot‐1, two codominant alleles forGot‐2andGot‐3, respectively. PGI isozymes are controlled by a single gene,Pgi‐1, with two codominant alleles. Altogether one invariant isozyme locus and six polymorphic loci are postulated. Test of joint segregation suggested a linkage ofDia‐3andPgi‐1. The reco