Electrophoretic variation of isoenzyme characters of ten enzymes (ADH, AAD, MDH, SKD, AAT, SOD, PRX, PGD, PGI, LAP) has been studied in five brome species, comprising the section Genea of the genus Bromus. The three polyploids, B. madritensis, B. rubens and B. diandrus (incl. B. rigidus), exhibited different fixed heterozygosities of several heterozymes, suggesting their alloploid nature. The morphologically similar polyploids B. madritensis and B. rubens differed in seven heterozymes out of fourteen studied, supporting their specific recognition. The two diploids, B. sterilis and B. tectorum, differed in four heterozymes. One genome of the polyploid species corresponded closely to that of B. sterilis. All species of the section could be distinguished from each other by diagnostic isoenzyme phenotypes. Bromus diandrus and B. rigidus revealed identical zymograms, providing new support for their conspecific recognition.