Tetraploid highbreed-cultivars of German chamomile differ significantly in their essential oil composition. In order to estimate the risk of genetic contamination resulting in quality losses, a population of 198 plants of the tetraploid /-/-alpha-bisabolol-type cultivar 'Manzana' was crossbred by open pollination with 2 plants of the bisabololoxide-containing cultivar 'BK-2'. The "bisabololoxide-content" is transmitted dominantly by the gene O/o. Five subsequent generations of this crossbreeding were analyzed and the results compared with expected values of the Hardy-Weinberg equilibrium for tetraploid organisms. The observed values showed a high correspondence with the theoretical ones in each generation, especially at calculation models presupposing 'BK-2' individuals with three to four dominant alleles and a potential crossing over during meiosis. According to the present results changes in quality of herbal starting materials are predictable and calculable.