The influence of the size and geometry of brewery fermentation vessels on beer flavour and aroma formation is generally attributed to carbon dioxide pressure. In order to study this pressure effect, brewery batch fermentations were carried out on the laboratory scale with Saccharomyces cerevisiae. The formation rates and yields of esters and fusel alcohols were studied in relation to the growth of metabolically active biomass. The results indicate that the observed reduction in the formation of esters and fusel alcohols with increased carbon dioxide pressure is mainly caused by reduced yeast growth. The overall formation of fusel alcohols is less affected than the formation of esters.