On completion of fermentation yeast slurry may be harvested from cone and stored until required for pitching into subsequent fermentations. The storage regime imposed upon the yeast cell may have a profound effect on yeast physiology and subsequent fermentation performance, though this is a strain dependent phenomenon. During storage the yeast may be subjected to physiological stress including starvation, cold shock, anaerobiosis (potentially leading to carbon dioxide toxicity), ethanol toxicity and the physical stresses associated with agitation. Although yeast cells held in storage typically exhibit stationary phase and therefore a degree of stress resistance, cellular deterioration may occur if the stress levels are combined or exceed the tolerance capacity of the strain. Extended storage can result in depletion of intracellular glycogen leading to a deterioration in yeast condition and impaired fermentation performance. The impact of temperature, time and agitation on the quality of ale and lager brewing yeast strains was examined during laboratory and brewery storage conditions. Yeast viability was analysed using brightfield and fluorescent stains, replicative capacity was assessed using the plate count. Yeast vitality was determined by monitoring glucose induced proton efflux and intracellular glycogen and trehalose levels. The impact of storage conditions on subsequent performance of the yeast slurries was examined during both laboratory and brewery production scale fermentations. Fermentation performance was assessed by monitoring four characteristics: replicative capacity (budding index after 6 hours fermentation); attenuation (rate and extent); flocculation (using the modified ethanol Helm's Test); and flavour development (including VDK reduction). It is generally accepted that successive fermentations in conjunction with periods of storage results in a progressive deterioration in brewing yeast physiological state. It is suggested that the response of brewing yeast strains to storage stress is strain dependent and determined by physiological history.