Harvested yeast from beers with high levels of bitterness units (BU) exhibited lower methylene blue viability values than did yeast harvested from beers with lower levels of BU. Aside from the hopping level, all other conditions for the fermentations were similar. Several months of production data were examined, and a pattern of lower viability from beers with higher BU was observed. The results of a bench-top fermentation study indicated a loss in viability with increased BU levels. The ASBC slide culture viability method featuring varying levels of hop extract showed that increasing BU levels exerted an adverse effect on the viability of harvested yeast.