The use of random amplified polymorphic DNA (RAPD) markers for evaluating seed purity in a commercial F1-hybrid cabbage (Brassica oleracea var. capitata) cultivar is demonstrated. Genomic DNA isolated from single ungerminated seed was found to be suitable for RAPD analysis. DNA from F1-hybrid and its parental lines was subjected to RAPD screening with 36 random decamer arbitrary primers. A total of 241 scorable products were observed with 54 (22%) being polymorphic. The RAPD data showed that the parental lines of this commercial cabbage cultivar were not very closely related. Two primers were chosen for purity testing of the F1-hybrid seeds. The sib (inbred seed; seed from self-pollination of parental lines) contamination results obtained by RAPD analysis were comparable to the commonly used grow-out trial and isozyme analysis, hence showing that RAPD analysis can be used for seed purity testing of commercial hybrid cabbage seeds.