An automated procedure for determining free amino nitrogen was developed by adopting the EBC- and ASBC-recommended ninhydrin method. The procedure was successfully applied to assess the contents of free amino nitrogen in the media at various stages of fermentation. Uptake of amino nitrogen and formation of fusel alcohols were studied in four experimental mashes which contained various amounts of nitrogenous compounds and carbohydrates. Results indicate that ale yeast takes up more amino nitrogen than lager yeast. Evidence also suggests that the bottom-fermenting yeast is capable of synthesizing more nitrogenous substances than the top-fermenting yeast under corresponding conditions. At the level of amino nitrogen examined (100–300 mg/l.), there is no positive correlation between the nitrogen concentration and the amount of fusel alcohols formed. More n-propanol and isobutanol but less 2-methyl-1-butanol were formed in ale than in lager brewed with the same wort. When an appreciable amount of sugar (mainly glucose) was added to the wort, the adjunct appeared to suppress the formation of n-propanol but promote that of 3-methyl-1-butanol.